The right option is Writers use character dialogue to reveal the theme in poems and plays.
A theme is a message that an author wants to send to his audience. Or in other words, theme refers to the main idea that the author is really trying to say. It can be explicitly stated or inferred and there are four ways in which an author can express themes: (1) through the actions or events in the story, (2) through the characters, (3) through the way the author makes us feel by sharing feelings of the main character and finally, (4) Themes are presented in thoughts and conversations.
Bearing in mind the described above, it could be said that Writers use character dialogue to reveal the theme in poems and plays since authors put words in their character’s mouths for specific reasons.