Which of the Following Techniques Has Been Used to Stimulate

Which of the following techniques has been used to stimulate people's thinking in response to a persuasive message?

A) Having different speakers present separate arguments rather than the same speaker present all the arguments
B) Using rhetorical questions such as, "Are you better off for having voted for so-and-so four years ago?"
C) Making people in the audience feel responsible for passing along the persuasive message
D) All of the choices are correct.