Answer: The should be A. Size and Physical strength are not the only measures of a person's value.
The detail that best reveals that Mr. Rainsford opposes Zaroff's idea of the ideal prey is Mr. Rainsford's response near the end of the passage when he states that he is a hunter, not a murderer. This statement shows the reader that Mr. Rainsford believes that Zaroff hunting humans as prey makes him a murderer.
This is a part of his supreme ordeal. His return home is much broader and includes his supreme ordeal which is what you described in the question. He fought them because he wanted to stop them from taking his wife Penelope. This was during the competition where they had to prove themselves.
hellno s ooy adqu isy dperu e oe