A comma splice is where two independent clauses (complete sentences) are joined together with a comma without also including a conjunction such as "and" or "but." Sentences B and D above both contain comma splices (the comma after "century" in B and the comma after "areas" in D). D is also missing a capital letter at the beginning of the sentence. The problem in sentence C is the commas surrounding the word "however." When the word "however is used to join two independent clauses like this, it should be preceded by a semicolon and followed by a comma. In this sentence, the semicolon belongs after the word "area." The word "however" begins the second independent clause. Thus, the only correct sentence above is A.
I think the answer is C because, in the beginning of her quote, she explains that you don’t need to be this special “person” or figure to be able to do something remarkable. Me Gies says, “People should never think that you have to be a very special person to help those who need you.”
I would do as you research. This way you can reference back to the sources as needed while you write your draft.
Hope this helped!