After an agonising moment, the audience applauded. I'm confused about the question but I hope this is what you meant. Sorry if I got this wrong
Answer:Form.
Explanation:
If you really think about, it cannot be of because it wouldn't really make sence with what you are thinking, to doesn't really make sence either, with neither makes sence. So the best choice would be form because it a form/ expression.
The last one: Provide Exposition