Answer:
The detail that best reveals that Rainsford opposes Zaroff's idea of the ideal prey is the line "Thank you, I'm a hunter, not a murderer."
Step-by-step explanation:
The characters Rainsford and Zaroff belong to the short story "The Most Dangerous Game" by Richard Connell. General Zaroff is a hunter who has grown tired of killing animals. To his mind, animals no longer represent a challenge to him since they do not have the capacity to reason. Zaroff lives in an island where ships usually sink. Those who survive become his prey.
Rainsford is also a hunter, and a rather famous one. He accidentally winds up at Zaroff's door and is recognized by the general. Zaroff thinks Rainsford will excitedly join him in hunting humans, but Rainsford is very straightforward in his decline:
"Thank you, I'm a hunter, not a murderer."
Rainsford is clearly more bound by morals and values than Zaroff, which makes him incapable of killing another human being for fun.
Zaroff makes Rainsford his prey and, for three days, hunts him in the forest of the island. Rainsford outsmarts him and kills Zaroff in the end.