Answer:
C. By studying demographics
In a sentence, the subject of the whole paragraph is the topic sentence.
When using quotes in an essay (which teachers often look for) make sure that the quote addresses the prompt. Also, make sure to use quotation marks and cite where the quote came from by using the authors surname and page number.
For example "The Dursley's of number four Privet Drive were proud to say they were perfectly normal, thank you very much." (Rowling 1).
