Final answer:
In O. Henry's 'After Twenty Years,' the key characters are Bob and Jimmy, who are central to the story's exploration of friendship and the passage of time.
Step-by-step explanation:
In After Twenty Years by O. Henry, the key characters are Bob and Jimmy. These two men are old friends who made a promise to meet at a specific place, exactly twenty years after saying goodbye. Bob arrives, expecting to reunite with his friend, while Jimmy, who is now a policeman, comes to fulfill the appointment in a twist that tests their friendship and the passing of time. The narrative centers around their meeting and the surprising resolution. This short story explores themes such as loyalty, change, and the impact of time on relationships. Unlike the characters provided in other options, such as Tom and Daisy from The Great Gatsby, Romeo and Juliet from Shakespeare's play, or Sherlock and Watson from Arthur Conan Doyle's detective stories, Bob and Jimmy are unique to O. Henry's work.