Answer:
Because it shows only what the narrator knows at any given point, it increases suspense and tension.
Step-by-step explanation:
In "The Pit and the Pendulum," Edgar Alan Poe makes use of the first-person point of view for readers to relate with the narrator and be able to understand his fears, emotions and motives. As a result, the audience can feel the narrator's anxious uncertainty as he goes through a lot of physical and mental distress.