Answer:
O Montresor is an unreliable narrator.
Step-by-step explanation:
This passage is narrated in the first person. As we know, Montressor, the narrator, is an unbalanced man and crazy for revenge. In his conception Fortunato would never be able to understand what his plans were and why he acted the way he did, but we are not able to know if this is true, through the narration of Montressor.
As we only know his perception of what happens in history, we do not know what is real and what is invented, so we can say that he is not a reliable narrator.