Answer:
C
Step-by-step explanation:
These kind of questions are extremely difficult to answer. There are 4 answers and none of them are completely correct.
You can eliminate D the quickest. The person talking about the plague is a clergyman, but nowhere does the author say anything about the role of the clergy.
I'm also of the mind that it is not really A. It is not exactly how quickly they buried the dead. More to the point is how quickly people could die once exposed to the black death.
At that time they didn't know the cause of the plague. It wasn't until much later that the cause was known. In the meantime, they did understand that sanitation and living conditions made the job of the plague much easier.
I think the best answer is C. The point was emphasized that it only took 3 days. That's not much time. Pick C.