The correct answer is D. "None, as on former occasions, aspired to the honor of walking by their pastor's side."
If you understood option D correctly, you could see why that is the correct answer. What it basically means is that nobody wanted to walk along with the pastor, not now, and not in the past. This means that the pastor is all alone, which tells us about the motif of isolation in this work. The other options do not even remotely mention loneliness and isolation.
The quote is taken from Nathaniel Hawthorne's "The Minister's Black Veil."
