Which one of the following statements about topic sentence and main idea is accurate?
a. a topic sentence is a central idea of a paragraph, while a main idea is the central idea of an entire text.
b. a topic sentence is found in the introduction, while a main idea is found in the conclusion.
c. a topic sentence does not change position, but the main idea can be found in multiple places.
d. a topic sentence and main idea are always the same.