Topic paragraphs get their punch from their topic sentence which is like?

This is one of a series of questions copied from Penn-Foster's "Practical English" quiz.There is no answer here.

When the topic sentence is last it is called a inverted triangle. The point being the topic, and the base being anything backing up the topic.

The sentences that restates the topic sentence.

Paragraphs like this are sort of like a vise versa (backwards.)

At the beginning or the end.