Question

Francisco: Nay, answer me. Stand, and unfold yourself.

Answer 1

I believe the third choice is the correct answer. In this expert, Francisco wants an answer, and wants to know an explanation. 

Answer 2

Answer: C) Explain yourself.

Explanation: In this line from "Hamlet" by William Shakespeare, Francisco, who is at his watch, demands the person that is approaching him (Barnardo, who comes to relieve him from the watch) to answer him, as Francisco doesn't know who the person is, he asks him to stand an unfold himself which means identify or explain himself, in this way he can be sure of who the person is.