Answer: I would contend that the right answer is actually the 3) “The thousand injuries of Fortunato I had borne as I best could, but when he ventured upon insult I vowed revenge.”
Explanation: Just to elaborate a little on the answer, it can be added that the other options do not specifically reflect the value that Montresor places on his reputation. Option 2 is a description of the Carnival costume and option 4 is an opinion about Montresor's family. In addition, in option 1 Montresor is stressing that, in relation to Fortunato, he has always acted moved by good will, but there is no reference to the value that he places on his reputation. It is only in option 3 where he hints at it—he tolerated Fortunato's endless injuries, but he could not accept being offended by him.