Which statement best captures the difference between central idea and topic in a nonfiction passage?

• A. Central idea is the author's message about the subject; topic is the subject itself.
• B. Central idea and topic are the same thing.
• C. Central idea is only a single fact about the subject.
• D. Central idea is the opposite of the topic.

Answer: (A)

The central idea is the author's main message about the subject, while the topic is the subject itself. So, a passage might discuss the topic of solar energy, but its central idea would express the author’s main point about it—such as that solar power is a practical, increasingly affordable energy source that can reduce dependence on fossil fuels. Details, examples, and reasoning in the text work to support that overarching idea, not to be the idea itself.

This distinction makes the statement clear: central idea = the author's message about the subject; topic = the subject matter. The other options mix up or reduce the relationship—for example, treating central idea as just a single fact, or as the opposite of the topic, or as the same thing as the topic.