Answer:
A. He is quiet, nervous, and uncomfortable around strangers.
Step-by-step explanation:
In the Open Window short story written by Saki, Nuttel is an "eccentric hypochondriac" visiting the country looking for someone to host him in their home, as for he needed a more quieter place to be relaxed and deal with his nerve issues.
Because of that condition of his, he seemed a man quite timid and uncomfortable around strangers: in the story, he easily believed a fake story about the tragic death of Mr. Sappleton and his children, told by a fifteen-year-old girl (and he did not even attempt to question her); he did not socialize well with Mrs. Sappleton and when the apparent dead relatives are in sight from the "Open Window" he fled the house immediately, horrified and scared, without saying a word.