Answer: “The lawyer proposes that he will remain in solitary confinement even longer than the banker suggests.”
Explanation: In the story, when the banker bets that the lawyer couldn’t bear to stay in a cell for five years, the lawyer lashes back, saying he could spend fifteen years if he wanted. The banker then bets two millions that he can’t.
(By the way, if you don’t feel you have the time to read a short story for your class over other more important assignments, summaries are a lifesaver. You can also listen to audio versions that might help you get the idea faster.)