Answer - C) stopped i think
Well
1) Hamlet is a prince
2) Not only is he a prince, but he is the prince of Denmark
3) Something tragic is going to happen because it's the Tragic History.
Keating is all about 'carpe diem', which means 'seize the day, go for it'. He encourages his students to live their lives to the fullest, the way they want to, and not to be restrained by anything. Having this in mind, Knox gathers the courage to go after the girlfriend of a football player, who was way out of his league.