What are topic sentences, and how do they function in structure analysis?

• A. Topic sentences introduce the main idea of a paragraph; they guide argument and coherence.
• B. Topic sentences summarize the entire essay.
• C. Topic sentences are optional and have no real function.
• D. Topic sentences are only used in narrative writing.

Answer: (A)

Topic sentences establish the paragraph’s main claim and act as a roadmap for the reader. In structure analysis, they help you identify what each paragraph is arguing or explaining and how that point connects to the overall thesis. A strong topic sentence states a clear point, and the rest of the paragraph provides evidence, reasoning, or examples to support that point. Because they signal the paragraph’s focus, they also support coherence, guiding transitions from one idea to the next and showing how each part contributes to the whole essay.

That’s why the option describing topic sentences as introducing the main idea and guiding argument and coherence is the best choice. They aren’t simply for summing up the entire essay—that’s more the role of a conclusion or abstract. They aren’t merely optional, since effective writing relies on clear, signposted claims in each paragraph. And they aren’t limited to narrative writing; topic sentences appear in argumentative and expository writing to organize ideas and analysis.