I am not sure if you are doing the same quiz as the other girl but this was her answer: Like a pig or a dog with ultra-sensitive nasal hairs, he was trying to pick up a scent. "He could smell something". Alternatively, his nostrils quivered as he took in air in readiness for an action, so possibly a preparation for an act of aggression.
My best guess would be C.
B.his bestfriend ,Arthur Hallam
