Question

What about the actions of these men exemplifies them as Hemingway heroes?
They talk about the oncoming attack, clearly with a deep sense of worry for their own safety and the safety of others.
They have not yet lived through a battle and are naive about the imminent danger that awaits them.
They have the bond only men in battle can share, and this is related by the way they partake of the cigarettes.
They act casually and go about regular business, such as smoking, while actually in grave danger.

Answer 1

They act casually and go about regular business, such as smoking, while actually in grave danger.

Explanation: Hemingway heroes display stoicism and "grace under pressure" — remaining composed, carrying out ordinary routines, and hiding fear in the face of danger. The men's calm smoking despite imminent peril exemplifies that code.