Answer: A) The pacing allows for a lengthy description of the man and clear description of the setting, which creates an alarming tone in the story.
Explanation: Pacing is a stylistic device, which shows how fast a story is moving forward. From the given options, the statement that best describes how the pacing of the passage from "After Twenty Years" by O. Henry affects the story, is the corresponding to option A: The pacing allows for a lengthy description of the man ("the man who had come a thousand miles to fill an appointment, uncertain almost to absurdity, with the friend of his youth, smoked his cigar and waited") and clear description of the setting (the weather, the people walking, etc.), which creates an alarming tone in the story.