Sentence C is the sentence that contains a dependent clause. If you were to break it up, it'd be, "Madison was also one of the authors of the federalist papers (independent clause) --which argued for the support of the constitution (dependent clause)."
Hope this helped. If not feel free to ask questions. *Tip*: watch out for spelling errors.
I am truly sorry if this is incorrect but... I believe it is due to the fact that Latin was popular and many people knew it and it was just overall considered a scientific language of sorts.
