Usually occurs during the conclusion of a story? a. the tension of the plot reaches its highest point. b. the action of the story reaches its turning point. c. the reader understands the characters' motivation. d. the reader finds out what happened to characters.

A conclusion is whenever the reader understands what motivates the character.

Therefore your answer would be,

The reader understands the characters' motivation.

C. The reader understands the characters' motivation.  

Explanation:

While the story's climax is what contains the plot's highest point of tension, a conclusion serves as closure to the story and to the character's developing personality. Once reaching this point, the reader will understand what inspired the character to develop in the story the way they did, as this provides closure for the process of characterization.