Answer: All answers are correct
After reading some other's opinions. It may be D. To be very impatient. But I could be wrong, and many apologies if I am.
Carl Sandberg is describing the pleasant feeling of being shrouded in fog and how it arrives gently, sits for awhile then moves on so is unobtrusive whereas Robert Frost in Mending Wall there is a strong skepticism about his neighbour's dictum that "good walls make good neighbours" and his feelings of misgivings about maintaining a wall between adjacent properties when there are no cows to corral or no obvious practical reasons for the wall.
The setting which begins to answer your question is the sentence that begins "Most conversations between husband and wife ... " this is near the beginning.
The real core of your question comes with "This aloofness ... " which shows how he handles the disputes with his wife. This is followed by "He attained this by ... " which tells exactly how the aloofness came about. Finally he surrounds himself with people that insulate him from the fights he has will his wife. His bridge games probably insure that he does not have to talk to her.
