Edgar Allan Poe has featured an old man (Montresor) spreading his tale of how cruelly the man killed another man (Fortunato), 50 years ago. The story is shaped with irony and development of dialogues in it cater the tale to its end. Moreover, the suspense and thrill are both the end result of the established irony in the language of this great writer.
The question, however, asks for the statement that proves the murderer's intention. So, I suggest you choose "option-C" because when they crept down towards the catacomb, Montresor mentions these lines. But, at this point, Fortunato has unfortunately lost his control over his own life. And, ultimately is chained and bricked into the wall.
