From the definition of absolute phrases we know that it is a modifier that attaches to a sentence without a conjunctution. So, we can say "his chubby legs, pumping" is the correct answer.
I am guessing on this, but I think that the answer is the body.
The part where Zaroff tried to include Rainsford in his sick hunting game would be the best portray Zaroff as Rainsford's foil i think.
Beside that, they both actually are very similar with one another
The definition of ardor is a way of feeling or acting that is energetic and exciting.
An example of ardor is a passionate speech.
-It was widely believed that tomatoes would incite ardor in those who consumed them
-I could not take my gaze off that beautiful face, which was all aflame with the ardor of love.
