Is a jury permitted to convict a defendant solely based upon circumstantial evidence?

Adefendant charged with driving while intoxicated pleaded not guilty and insisted on a trial. right before the trial began, he fired his attorney and decided to defend himself. at one point during opening arguments, the defendant began to act like a cat, meowing and chasing an imaginary squirrel out of the courtroom. if no one else raises the issue of the defendant's competency to stand trial, what is the responsibility of the trial judge here? a) the trial judge has no responsibility, because the defendant decided to defend himself. b) the trial judge has no responsibility, because she cannot decide whether the defendant is competent to stand trial. c) the trial judge must raise the issue of competency, because the defendant is representinghimself. d) the trial judge must raise the issue of competency, because the constitution obligates her to do.