In "The Most Dangerous Game," what choice does Zaroff give Rainsford before the hunt?

In Richard Connel's short story "The Most Dangerous Game" Sanger Rainsford, a big game hunter, accidentally falls off his yacht into the ocean near an island named "Ship-Trap" island. While on the island he comes across the chateau of Zaroff, a former Russian general who lives on the island to indulge in his one passion in life, hunting. Unfortunately, Zaroff, who has grown bored with hunting animals, now hunts humans, sailors who are ship wrecked...

In Richard Connel's short story "The Most Dangerous Game" Sanger Rainsford, a big game hunter, accidentally falls off his yacht into the ocean near an island named "Ship-Trap" island. While on the island he comes across the chateau of Zaroff, a former Russian general who lives on the island to indulge in his one passion in life, hunting. Unfortunately, Zaroff, who has grown bored with hunting animals, now hunts humans, sailors who are ship wrecked on the island. 

When Zaroff asks Rainsford to hunt with him, Rainsford refuses and calls it "cold-blooded murder." He demands to be released from the island and given a boat to the mainland. Since Rainsford won't hunt with him, Zaroff decides he will hunt Rainsford. Zaroff is anxious at the thought of matching wits with another hunter. He says,

"You'll find this game worth playing," the general said enthusiastically. "Your brain against mine. Your woodcraft against mine. Your strength and stamina against mine. Outdoor chess! And the stake is not without value, eh?" 

Rainsford's only other option is to fall into the hands of Zaroff's servant, a cossack and former torturer for the Russian army. Zaroff describes the potential fate with Ivan:

"If he does not wish to hunt, I turn him over to Ivan. Ivan once had the honor of serving as official knouter to the Great White Czar, and he has his own ideas of sport. Invariably, Mr. Rainsford, invariably they choose the hunt." 

Zaroff also guarantees that if Rainsford outwits him and is not captured or killed within three days he will release him to the mainland. With no other choice Rainsford strikes off into the jungle armed only with a "supply of food and an excellent hunting knife."