Alex was called a grand jury witness in an investigation about a terrorist attack on a subway station. When asked about the purchase of 500 pounds of ammonium nitrate, Alex responded that he had done so on behalf of a third party. When asked the name of the third party, Alex took the Fifth Amendment. The prosecutor argued that Alex could not do so.

Is he right?

a No, because he revealed incriminating information about a third party and not himself

b Yes because Alex had already disclosed incriminating information regarding the terror plot and this barred his reliance on the Fifth Amendment

c Yes, because this is a grand jury proceeding and not a trial

d No, because there was a clear potential for additional incrimination since Alex's guilt or innocence could depend on the testimony of the witness he was asked to identify