English ACT Aspire Practice Test 2026 – All-in-One Guide to Exam Success!

A topic sentence serves as the focal point of a paragraph, encapsulating the main idea or theme that the paragraph will discuss. It is typically positioned at the beginning of the paragraph to clearly convey the primary message to the reader. By establishing what the paragraph will elaborate on, the topic sentence guides the reader’s understanding and sets the context for the supporting details that follow.

The other options reflect different aspects or functions of sentences within a paragraph but do not define what a topic sentence is. The concluding sentence summarizes the main points but does not introduce or indicate the main idea. Similarly, a sentence that provides details supports the paragraph's main idea but is not the topic sentence itself. Finally, a sentence that introduces conflict does not relate specifically to the concept of a topic sentence; rather, it could be part of a narrative or argument structure that involves tension or disagreement but does not encapsulate the main idea of a paragraph.