In what way is Zaroff portrayed as Rainsford’s foil?

Zaroff has no conscience, while Rainsford does have a conscience.
Zaroff is an enthusiastic hunter, while Rainsford is indifferent to hunting.
Zaroff is an inconsiderate host, while Rainsford is a very good guest.
Zaroff has little hunting experience, while Rainsford has a lot.
Read the excerpt from "The Most Dangerous Game."

"I can't believe you are serious, General Zaroff. This is a grisly joke."

"Why should I not be serious? I am speaking of hunting."

"Hunting? General Zaroff, what you speak of is murder."

The general laughed with entire good nature. He regarded Rainsford quizzically. "I refuse to believe that so modern and civilized a young man as you seem to be harbors romantic ideas about the value of human life. Surely your experiences in the war—"

"Did not make me condone cold-blooded murder," finished Rainsford stiffly.