Answer:
D.
Step-by-step explanation:
A topic sentence can be defined as a sentence that sums up the main idea of a text or paper. A topic sentence sepcifies the topic to be clarified in the paragraph.
A topic sentence appears in every paragraph of a text. By stating topic sentence in every paragraph, the writer specifies the main idea that he/she will discuss in the paragraph.
Therefore, from the given options, correct one is D.