The correct answer is: The author uses fast pacing to introduce tension, then slows the pace.
In the story, the initial race for the elevator and the interactions between the two characters are characterized by fast pacing, creating a sense of urgency and tension. Once the power goes out and they find themselves stuck, the pacing slows down, allowing for a moment of reflection and silence as each character processes the situation. This manipulation of time enhances the emotional impact of the narrative and draws attention to the characters' backstories through flashbacks.