Rawi is analyzing a writing prompt and decides that he must write a five-paragraph essay to fully describe his point of view. rawi has just determined his essay’s a. format. b. topic. c. audience. d. purpose.

I believe the correct answer is A. format.
He realized that he needs to write an essay which contains five paragraphs, which relates to the format of his essay. We don't see his topic or his audience here, and we still don't know what the purpose of his essay is, so I believe A is the only correct answer.