In the Context of the Elements of Persuasion, a Communicator

In the context of the elements of persuasion, a communicator is considered credible if

A) he or she uses "you know" or "uh" when speaking or stumbles over his or her words.
B) he or she is able to convince people that he or she is trying to persuade them.
C) he or she speaks slowly and haltingly.
D) he or she is seen as knowledgeable on a topic.