Answer:
O Teach the reader a moral lesson.
Step-by-step explanation:
Any form of literary work tends to have a theme that resonates with what the writer wants to relay as a message to the readers. This purpose of a "theme" is thus, to provide a moral lesson through the story.
A theme is a central topic around which the whole story revolves around. Writers employ themes to pass on a message in their stories, be it a moral lesson or any message that they want to help spread. Themes are a particular favorite of morality plays which mainly focus on the Christian belief of goodness and humility. William Shakespeare's play "Macbeth" can be taken as an example of a theme based on 'good vs. evil'.