The correct answer is C. Fortunato thinks himself to be a better connoisseur of wines than Luchesi.
Fortunato considers himself to be a great connoisseur of wine, and he thinks Luchesi is a fraud. He believes that Luchesi misidentified cheap wine as Amontillado, and he wants an opportunity to prove he is right and Luchesi is wrong.
Note that the difference between answer A and answer C is Fortunato's belief. Answer A states Luchesi's lack of knowledge as fact, but we do not know if this is actually true. However, Fortunato THINKS he is better than Luchesi, and that's what makes him go down into the cellar despite the cold, as indicated by Answer C.
Because Fortunato believes himself to be better than Luchesi, he will leave the celebrations and brave the coldness of the crypts. Ultimately, his pride will lead to his death.