The answer to this question is letter B. He is confident that it is JUST (worthy or right) cause to be fighting for. There are a lot of soldiers who join the war not because they were forced to do so or because they felt that they have nothing better to do. Some of them joined because they truly wanted to. They felt that it was their duty in order to protect not only their country but also their people.
They all want to live but they also know that what they are doing is worth dying for. There are a lot of soldiers who experience a lot of trauma when they are exposed to the war. They come back as changed men with views that are different as compared to when they first entered the service.