What would grammatically fit here?
Henry Adams, born in Boston, _________ famous as a historian and novelist.

The correct answer to this question is A. We can identify that it has a complimentary phrase between commas. The main subject is complete. After the blank there are phrases only, which means it does not have a main verb.

Looking at the incorrect answers, we know it is not answer B because it has a conjunction, it is not answer C because it has a subject, and it is not answer D because the sentence has both a conjunction and subject. Indeed, history tells us that Henry Adams was born in Boston and became famous as a historian and novelist.