Answer:
The correct answer would be option b:"The author once felt pride and optimism about the war".
Explanation:
In the excerpt, the author says that "he was proud of the young American pilots sitting at the controls in the cockpit" and that "he was grateful for the opportunity to witness this adventure and report it".
It just says that he was excited to get on a U.S Army helicopter, it does not say nor infer that is was his first flying experience, therefore, option a is incorrect.
It doesn't say and it cannot be inferred that the U.S soldiers are trained in hand to hand combat, so option c is also incorrect.
The author barely mentions the Vietcong guerillas, and he does not seem to have any respect for them since he was excited about war, so option d is also incorrect.