Answer:
Could you please add a link? I don't know how you are supposed to answer.
Explanation:
The correct answer is C, due to the fact that Buck's life and emotions are very similar to humans, as Buck's life is an allegory of human lives.
A plot diagram is the answer
I know the answer isn't C or D. A or B both seem likely until you see that B involves a 'comma without a conjunction,' either way you should never put a comma before 'and'; I am not sure why but I am pretty sure this only applies in a formal document. So your answer is A.