Answer: B. It gives O. Henry a way to keep key information about both main characters hidden until the end.
"After Twenty Years" is a short story by O. Henry. It was first published in his anthology The Four Million in 1906.
It tells the story of two friends who due to their separate paths in life have not seen each other in twenty years. However, they have agreed to meet on a particular spot near a restaurant that night. The story has a plot twist near the end, which relies on the author keeping information about the main characters hidden until the end. He does so by means of a third-person narrative.