Question

read the excerpt from hemingways a farewell to arms
the major asked me to have a drink with him and two other officers. we drank rum and it was very friendly. outside it was getting dark. i asked what time the attack was to be and they said as soon as it was dark.
the casual behavior of the characters during a difficult time demonstrates hemingways belief that a hero should
exhibit grace under pressure
recognize the meaninglessness of life.
have a mentor to follow.
learn from his mistakes.

Explanation:

In the excerpt, the characters are in a situation where an attack is imminent (a difficult time). Their casual behavior (drinking rum and being friendly) shows composure. Hemingway often emphasized grace under pressure in his works. The other options: recognizing the meaninglessness of life isn't shown here (no nihilistic statements), having a mentor - there's no indication of a mentor - mentee relationship, and learning from mistakes - no mention of past mistakes.

Answer:

exhibit grace under pressure