What should a speaker do to best appeal to an audience

The answers is: C. Understand the audience's expectations and knowledge base.

Explanation:

In order to feel attracted or attached to something or someone, your firstly look up for comprehension. When something seems to relate to you or understand what you mean, you are most likely to respond positively and feel  more engaged to that. So this is the most important thing you would like to do if you want to actually appeal to an audience, have a background knowledge of them and undesrtand why are they there and put yourself in their shoes; if it were you, what would you expect?

The other options are simply depending on your audience's needs. Perhaps they might want to actually have very detailed information to retain as much as possible, or perhaps they might feel more engaged asking questions, etc... but in general terms,  it all depends on option C.

b. b. b. is the anoswer