
317 S.E.2d 385 (1984)
STATE of North Carolina
v.
Theodore Morris FOUST.
No. 624A83.
Supreme Court of North Carolina.
July 6, 1984.
*387 Atty. Gen. Rufus L. Edmisten by Sp. Deputy Atty. Gen. Isham B. Hudson, Jr., Raleigh, for the State.
Asst. Appellate Defender Ann B. Petersen, Raleigh, for defendant.
COPELAND, Justice.
Defendant brings forward three assignments of error which he contends require a new trial. We disagree and affirm the sentences imposed.
Under the first assignment, the defendant contends that the court erred in permitting the State to introduce evidence concerning the percentage of rayon fibers produced in the United States, on the grounds that such evidence was inadmissible hearsay as well as irrelevant.
*388 As part of its case in chief, the State presented testimony from F.B.I. Special Agent Blythe, who had been qualified as an expert in the field of hair and fiber analysis and identification. As stated earlier the Agent opined that the fibers found on the victim's clothes could have originated from the defendant's bedspread. Defense counsel objected to the following testimony elicited by the prosecutor on direct examination:
Q. Have you done any comparison, checking in light of your duties and responsibilities as a fiber analyst into the amount of use of rayon in fabrics?
A. Yes, sir, I have.
Q. And do you have an opinion based on your research and investigation into this matter as to how commonplace the use of rayon fabric is in the textile industry?
MR. HARRELSON: Objection.
THE COURT: On grounds of expertise?
MR. HARRELSON: Yes. He said he did some checking, but he hasn't shown what extent it was done.
MR. COMAN: Does he want to ask him about the research?
MR. HARRELSON: I don't want to ask him about anything. I think the burden is on you.
THE COURT: Well, the objection is overruled. The Court holds he is in a better position than the jurors to form such an opinion.
BY MR. COMAN:
Q. Go Ahead, Agent Blythe.
A. I did some checking of data that we have in the FBI Laboratory concerning the use of both polyester and rayon fibers as are in relation to the production of these synthetic fibers in the United States.
Q. All right. What would that percentage be?
MR. HARRELSON: Objection.
THE COURT: Overruled.
You may answer, if you know.
THE WITNESS: Based on the latest information which I could findThis is 1979 statisticsRayon comprised slightly less than six and a half percent of all the man-made textile fibers produced in the United States.
The defendant argues that the challenged testimony misled the jury by giving them the impression that since rayon is seldomly used, the fact that the fibers from the bedspread and from the victim's clothes contained rayon was highly significant to the defendant's guilt. Defendant reasons that the State wanted to show that while the tests performed by Agent Blythe were inconclusive, there was a high probability that the fibers found on the victim's clothing did in fact originate from the bedspread. The defendant concludes that the State accomplished its goal when the agent was permitted to testify with regard to the actual percentage of rayon in American made textile fibers.
The record discloses that prior to the objected testimony being offered, Agent Blythe testified, without objection, that "[b]ased upon my experience, the use of polyester is quite common, but the use of rayon is becoming more and more less common." Further, the overall implication gathered from the agent's testimony was that the fibers from the clothes came from a bedspread constructed using the same materials.
Assuming, arguendo, that the challenged testimony was improperly admitted into evidence, we believe the defendant has failed to show actual prejudice. An erroneous admission of evidence is prejudicial, or reversible error if "there is a reasonable possibility that, had the error in question not been committed, a different result would have been reached at trial ..." N.C.Gen.Stat. § 15A-1443(a); See: State v. Corbett, 307 N.C. 169, 297 S.E.2d 553 (1982) and State v. Wood, 306 N.C. 510, 294 S.E.2d 310 (1982), later app., 310 N.C. 460, 312 S.E.2d 467 (1984).
Given the overwhelming evidence against the defendant, it is clear that the error, if any, was harmless. Accordingly, defendant is not entitled to relief from this assignment of error.
*389 Defendant next contends that his constitutional rights were violated during the State's final argument by the prosecutor improperly commenting on defendant's failure to testify. The prosecutor made repeated references to the fact that the evidence presented by the State was "uncontroverted" or "uncontradicted." Defendant construes the prosecutor's remarks as a comment on the defendant's failure to testify. We do not agree with this contention.
Under the Fifth and Fourteenth Amendments, the defendant has a right to remain silent, thus any comment by the prosecutor on the defendant's failure to take the stand and testify is impermissible. Griffin v. California, 380 U.S. 609, 85 S.Ct. 1229, 14 L.Ed.2d 106, reh. den., 381 U.S. 957, 85 S.Ct. 1797, 14 L.Ed.2d 730 (1965); State v. McCall, 286 N.C. 472, 212 S.E.2d 132 (1975), later app., 289 N.C. 512, 223 S.E.2d 303, vacated in part, 429 U.S. 912, 97 S.Ct. 301, 50 L.Ed.2d 278 (1976). However, the State may, in its closing argument, properly bring to the jury's attention the defendant's failure to produce exculpatory evidence or to contradict the State's evidence. State v. Jordan, 305 N.C. 274, 280, 287 S.E.2d 827, 831 (1982); State v. Williams, 305 N.C. 656, 675, 292 S.E.2d 243, 255, cert. den., 459 U.S. 1056, 103 S.Ct. 474, 74 L.Ed.2d 622 (1982). We interpret the challenged arguments of the prosecutor to be directed at the defendant's failure to offer evidence rebutting the State's case rather than directed at his failure to take the stand. Defendant asserts that since the defendant was the only available witness who could have contradicted the State's evidence, the prosecutor's comment must be construed as a comment on the defendant's failure to testify. In evaluating a prosecutor's argument that the State's case was "uncontradicted," we do not consider the unavailability of witnesses for the defense to be a determinative factor. This is not a case where evidence, necessary to contradict that of the State, would have to come from the defendant himself. Here, the State's evidence consisted of considerably more than the victim's testimony of what happened. There was testimony involving, for example, the fibers found on the victim's clothing and the results of the physical examination made of the victim. There was evidence relating to the victim's conversation with his mother immediately after the assault, the victim's statement to investigators, and various items allegedly found in defendant's apartment. Much of this evidence was theoretically contradictable by testimony of persons other than defendant. For this reason the prosecutor's arguments do not constitute a comment on defendant's failure to testify.
The record reveals that defense counsel did not object to any of the prosecutor's argument concerning the State's "uncontroverted" evidence. However, in his closing argument he carefully, and effectively we believe, reminded the jury that the State had the burden of proving each and every element of the crimes charged. The trial court, in its charge to the jury, instructed that a defendant is presumed to be innocent and that the burden of proof was on the State. Any alleged prejudice that may have resulted from the challenged remarks, were removed by the judge's additional instructions:
In this case, the defendant has not testified. The law of North Carolina gives him this privilege. This same law also assures him that his decision not to testify creates no presumption against him. Therefore, his silence is not to influence your decision in any way.
This assignment of error is overruled.
As his third assignment of error, defendant challenges the trial court's instructions on the offense of first degree sexual offense. He contends that these instructions deprived him of his right to a unanimous verdict, by permitting the jury to return a verdict of guilty without being unanimous about which particular criminal act defendant committed.
The indictment charged the defendant with unlawfully engaging in a sexual act with the prosecuting witness, without specifying *390 what act was performed. The State's evidence tended to show the commission of two distinct offenses of first degree sexual offense, to wit, anal intercourse and fellatio.
The trial judge instructed that the State was required to prove four elements beyond a reasonable doubt, the first being that a sexual act occurred. A sexual act was explained as meaning oral sex or anal intercourse. After properly advising the jury as to the remaining three elements, the trial judge then instructed that the jury must return a verdict of guilty if they found that the defendant engaged in "oral sex or anal sex" with the victim and if they found all the other elements of first degree sexual offense.
It appears, from a disjunctive reading of the trial court's charge, that such instructions would allow the jury to return a guilty verdict if they found that defendant committed either of the distinct offenses, without requiring that all twelve members agree as to the guilt on at least one of the offenses. Defendant argues that possibly six of the jurors could have found him guilty of anal intercourse, while the remaining six jurors could have found him guilty of the act of oral sex. Thus, under these circumstances, there would be no unanimity among the jurors as to the specific crime committed.
However, the trial judge continued his charge to the jury on the sexual offense with the following instruction:
However, if you do not so find or if you have a reasonable doubt as to one or more of these things, it would be your duty to return a verdict of not guilty as to this charge.
The trial court clearly informed the jurors that they must agree on all the elements before a verdict of guilty could be reached. However, immediately thereafter, the jury was given instructions on the requirement of unanimity.
Your verdicts must be unanimous. You may not take a vote by majority, but all twelve of the retiring jurors must agree as to what your verdict will be in each case.... It is your duty to reason together with your fellow jurors, to discuss the evidence at some length until you feel there is some consensus about the facts ...
These instructions, when read as a whole, obviously required a verdict of not guilty if all twelve jurors were not satisfied beyond a reasonable doubt that the defendant participated in either fellatio or anal intercourse, or both. We believe the evidence amply sustains a conviction for either or both offenses. Nothing in the record indicates any confusion, misunderstanding or disagreement among the jury members regarding the unanimity of the verdict. The convincing inference is that the jury unanimously agreed that defendant engaged in both oral and anal sex.
This Court has considered a similar argument in State v. Hall, 305 N.C. 77, 286 S.E.2d 552 (1982). There the bill of indictment charged the defendant with one count of armed robbery involving the taking of personal cash from the gas station attendant and from the gas station. The State's evidence that the defendant took both the money belonging to the attendant and the property of the gas station owner, resulted in defendant's conviction. The defendant argued that the failure of the trial court to instruct the jury that it must unanimously find that defendant committed both takings was error. We found defendant's contention that this instruction deprived him of his right to a unanimous verdict unpersuasive.
Although we are satisfied that the defendant, in this case, was not deprived of his right to a unanimous determination of his guilt, it is the better practice that trial judges in cases involving first or second degree sexual offenses, submit separate issues of each unlawful sexual act if more than one act exists. This procedure would eliminate any possible confusion or claim of error with respect to the jury's verdict as to the particular transaction that constituted the unlawful sexual act. We recommend that in the future trial judges abide *391 by this practice of submitting separate issues.
We have carefully examined all the assignments of error and conclude that no prejudicial errors were committed.
Accordingly, we find no error.
