A topic sentence captures the key idea of the paragraph. This sentence would help the readers understand the objective of the paragraph and also helps them tie the passage with the other paragraphs and the overall essay.
Example:
Undeniably, abortion is a terrible thing. The question is not whether abortion is good; the question is whether it should be allowed. There are many people who do not believe in “necessary evil”. There are people who believe that if a woman becomes pregnant, that child should be born no matter the circumstances. As a result, the child is required to face the consequences of the parents’ actions, even if they might suffer. Is it fair to the child to be born in an inhospitable environment? No child should ever question whether or not he or she should have been born.
Topic Sentence of above exam