The answer is option B or " It explains the main point by using a comparison." In this case we have a passage about writing a good essay, and it gets to that point by comparing it to your body. It's not option D because it's not describing anything nonhuman with human attributes, it's not option A because it's not referencing a famous example the passage is comparing a essay to a human body and how to think of a essay as one. It's also not option C because again it's comparing two things not making any statements about anything.
