I would say that the question most likely to be answered by reading the exposition of a story is C:<em> </em><em>How has the author's life affected what he or she is writing?</em>
Explanation:
In a exposition, the reader can learn about the events, the context in which that piece was created. They can learn about those facts that may be are not part of the story, but that are crucial to understand why the story or the characters develop the way they do. By knowing the context, we can learn about the time the author was going through during the creating process and why the story turns out to be the way it is.
