what is the first sentence of a body paragraph called? thesis statement background topic sentence claim

Brief Explanations:

In writing, the first sentence of a body paragraph is called a topic sentence. Its purpose is to introduce the main idea of the paragraph. A thesis statement is the main argument of an essay (usually in the introduction). Background provides context (not necessarily the first sentence of a body paragraph). A claim is a statement that something is true (but not specifically the first - sentence - of - a - body - paragraph term).

Answer:

C. Topic sentence