How does Norma's arguement with Arthur in paragraphs 90-116 build suspense

This question is about "Button, button" written by Richard Matheson.

Norma's argument imposes unpredictability on how the story will develop. The reader cannot imagine if they will press the button, if someone will die or if the box will solve or cause a problem. This causes tension in the reading and a feeling that anything can happen at any time, thus generating suspense.

Explanation:

Norma and Arthur are a couple who are facing many financial problems, one day they receive a mysterious box with the button. If they press the button they will receive 50 thousand dollars, but this will cause a person to die. Arthur and Norma are very doubtful if they press the button and cause someone to die, although Norma seems more willing to do so. However, the entire narrative is governed by unpredictability, causing a feeling of suspense and apprehension, as the story may follow several unpredictable paths.