The theme of a story is the author's main idea or message. It usually is some type of message about life. It is not a main idea or topic statement. The last option that says what the story is about is a topic statement not a theme. Preferring art or music to sports is also not an effective theme because it isn't really something that needs to be learned. On this note, neither is the third option. Sports participation boosting self-confidence is a message or idea the author may want to share with the readers. This best fits the idea of theme because it is not a topic statement and it carries a message.
