Answer:
C.
1- "When I had answered the Count, I looked in the mirror again, trying to figure out how I could have been wrong." This shows that the narrator is trying to analyze the event of the Count appearing behind him in the mirror.
2- The narrator first believes that he must have been mistaken about the Count not being reflected in the mirror.
3- The adverb "only" in line 24 shows the failure of this explanation, as it implies that there was no other possible explanation for the Count not being reflected in the mirror.
4- The event can be qualified as strange or inexplicable.
D.
1- "He" is the subject of the verb "grabbed" and it replaces the Count. "Me" is the COD of the verb and it replaces the narrator.
2- The narrator wishes to get out of the castle and escape the strange events that are happening there. This can be seen in the proposition "I would like to get out... or have never been there!"
3- The narrator is not sure that he was assaulted, as indicated by the phrase "I only had to turn my head slightly to see him against my shoulder." This suggests that the narrator was not sure if the Count actually grabbed his throat or if it was just his imagination.