The answer is...
<span>Fortunato thinks Montresor has played a joke on him.
</span>
He literally is so drunk, that he doesn't understand that his "friend" was building a wall to cover up the room where he had chained him inside the catacombs. IF he were to be hoping that this is all a joke (second choice) He would be able to understand the situation, wouldn't be laughing... and try as hard as he could to get out. In this case he is just laughing at the "joke" his "friend" has played on him.
Good Luck! :)
2nd Option: He writes about the pure innocence of nature.
D ( the last one ) because fog settling into your brain is figurative language.
