The purpose of theme is to -- O clarify the topic of a literary work
O convey the author's attitude toward a subject
O reveal an insight about human life
O teach the reader a moral lesson

O Teach the reader a moral lesson.

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'.

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