Answer: B) To describe plot.
Step-by-step explanation: The theme of a story or a text is a universal idea, lesson, or message explored throughout the work of literature. The plot is a literary term used to describe the events that make up a story, or the main part of a story. The given sentence has the function of stating theme, because it is an example of a lesson or a message to the audience that an author can include in his/her work.