B. Though Benjamin Franklin was known for his instrumental role in the founding of the United States.
This is a sentence fragment, you can tell because saying the sentence in your head or out loud feels incomplete, that is because the sentence wasn't finished, for example, "Though Benjamin Franklin was known for his instrumental role in the founding of the United States, he had many other accomplishments." Is a full sentence.
Introduction
Hope u had a good day.
The last sentence about reliving the writers younger days as in memories