Which of the following is an effective strategy for convincing an unwilling audience?
a. use parallel phrases
b. repeat keywords for emphasis
c. build your argument
d. vary the pitch of your voice

The correct answer is C. You should always, especially with an unwilling audience, build your argument. That means thinking logically, supporting your claim with explanations and clear as well as concrete examples. The reason is that logical reasoning can make the audience understand why what they believe is not entirely true, or why there are other points of view that should be considered. The other options could be found in an speech or argumentative text, but they are no crucial to convincing the audience, though they do contribute.