C. & D.
He killed himself because he could no longer tolerate the horrors of war, his own psychological abilities to deal with the horrors had turned on himself, so that he took his own life. And unlike a normal situation in life, the war had made it so that life and meaning were no longer relevant. They did not recognize the value of his life dead or alive, demonstrating another mental loss in the psychology of warfare.
Hurting others won’t fix your problems.
Putting others down won’t bring you up.
None of the answer given fits the questions " An argument may warrant additional support in the form of additional evidence when." A is not logical for the questions, C, is only an opinion by an expert and is not based on fact, and B doesn't fit. The correct answer is D.