Which of the following best describes the role of a topic sentence?

The role of a topic sentence is to clearly state the main idea of a paragraph, which helps the reader understand what the paragraph will be about. A strong topic sentence sets the direction for the rest of the paragraph by introducing the subject matter, allowing the reader to comprehend the focus and purpose of the upcoming information and arguments. This is essential in guiding the reader through the text and providing a framework on which supporting details and examples can build.

In contrast, while some elements like conclusions or summaries may appear in other parts of a text, they do not define the function of a topic sentence. Similarly, while supporting details are important for elaborating on the main idea, they are not encapsulated within the topic sentence itself. The topic sentence serves exclusively as the foundational statement of the paragraph's core concept.