During a Q&A Session After His Speech, One of the Audience

During a Q&A session after his speech, one of the audience members asks Drew a question he doesn't know the answer to. How should Drew handle this situation?

A) He should take his best guess.
B) He should discreetly try to change the subject.
C) He should admit that he doesn't know the answer, but promise to get back to the person later.
D) He should ask the audience if anyone else knows the answer.