A topic sentence is a sentence that includes the main idea of the paragraph.
It is a sentence that is usually found in the beginning of a paragraph, although not always. It is the sentence that states what the main idea of that particular paragraph is, and then the paragraph is there to support this sentence, not the other way round.
Answer: Well..
Explanation:
Since you don't have important answer choices up I'll just tell ya what I know. The title will give you an idea, plus certain words will too.
<h2>HERE'S THE ANSWER!!</h2>

<h3>QUESTION:</h3>
- The relation of plants and living creatures to each other and to their environment; the study of this.
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<h3>ANSWER:</h3>
<h3><u>✔︎</u><u> </u><u>ECOLOGY</u></h3>
- Ecology, also called <em>ecological science</em>, is the biological study of the relationship of plants and living things to each other and to their environment.
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(^_^メ)
Hi, Im Daubechies, a Filipina user ≧▽≦