Answer:
A. The narrator is haunted by a man's eye.
Step-by-step explanation:
Although all the other options are true descriptions of what the narrator of the story is like, none of them would make the narrator unreliable. However, option A does. Option A states that the narrator is haunted by the man's eye. This is not a normal reaction to a man's eye, no matter what the eye is like. Therefore, from this behaviour, we can conclude that the man is insane, or that he is at least somewhat mentally unfit.