Answer:
The author use dialogue in this excerpt because The dialogue slows the pace of the narrative to delay the outcome.
Step-by-step explanation:
This part of "The Cask of Amontillado." by Edgar Allan Poe, distracts the attention from the future events through a simple conversation aside, that has not much to do with the real feelings and intentions of the characters and to the irrevocable outcome of the story, later on, the following events are not as light as this excerpt.