According to the text, we can say that Wallace chose to choose his career and life because he was happy in the real world and the happiness behind the green door was fleeting.
We can arrive at this answer because:
Wallace felt great behind the green door, but that happiness was fleeting and didn't last when he returned home.
In that case, he was left with an extreme feeling of sadness and melancholy and that was a very bad feeling.
However, starting a college, having contact with people, and planning his own life and career, was something that made Wallace happy, and that happiness was maintained.
Wallace thought that happiness in the real world was more stable, as it was a happiness that depended on him and that he could have it wherever he went.
The correct answer would be - A. The ring was too tight for my finger. If you say both of the sentences out loud you can hear which one is a sentence someone would say in conversation and which one sounds incorrect. Hope this helped!