Some paragraphs build up to a main idea, so the topic sentence is at the ?

A topic sentence is a sentence that expresses the main idea of the paragraph in which it occurs.

Explanation:

In expository writing the topic sentence is the sentence that summarizes the main idea of a paragraph. It usually is the first sentence in the paragraph. In my opinion the topic sentence should be the first sentence, this way the reader can easily understand what the expository writing is about. This is also known as a focus sentence, which encapsulates or organizes an entire paragraph.

he is a confident leader.