Final answer:
A topic sentence expresses the main idea of a paragraph, while a thesis statement expresses the main idea or claim of an essay. Therefore, the correct option is C.
Step-by-step explanation:
A topic sentence is a single sentence that expresses the main idea of a paragraph, while a thesis statement is a one to two sentence statement that expresses the main idea or claim of an entire essay. A topic sentence is typically found at the beginning of a paragraph and helps to maintain focus and unity within that paragraph.
On the other hand, a thesis statement is usually found at the end of the introduction of an essay and provides a roadmap for the entire paper, stating the main argument and the aspects that will be covered.