Answer:
A. in the exposition
B. anytime the story changes location
C. anytime the story shifts into a different period of time
Step-by-step explanation:
A setting of a book, or narration is the location or time of where the present action is happening. It helps to create and dictate the mood of a story.
The best time for an author to describe the setting of a book or action is when he wants to heighten mood.