What is the function of a topic sentence?

A topic sentence serves as a crucial component in the organization of a paragraph. Its primary function is to summarize the main idea, providing the reader with a clear understanding of what the paragraph will discuss. By presenting the central theme right at the beginning, the topic sentence sets the tone for the details and examples that follow, helping to maintain focus and coherence throughout the paragraph.

While other options may describe aspects relevant to writing, they do not align with the specific role of a topic sentence. Introducing a setting, presenting a counterargument, or offering background information may arise within the context of a paragraph but do not encapsulate the overarching purpose of a topic sentence, which is to clearly communicate the main idea.