The story likely takes place during the civil war in the United States. The Rostina Sharpshooters were a regiment of soldiers (all of whom were marksmen meaning they could hit what they aimed at). The men in question are being shot at by these sharpshooters who must be too far away even for them. But the men are quite nervous about what they are doing.
If you consider this an example of very black humor, then E is your answer. Certainly the men are uneasy. They feel comfortable about nothing that is going on. They are hesitant to search the body. They are very tentative about how to deal with the service. They can't make up their minds if they should continue with the body or wait until the next day. They can't remember the service. Everything about this scene is delay, discussion and a hesitant move forward. They even have trouble with where to put the first few shovelfuls of dirt. You have to pick uneasy.
You have to pick E, but if it is humorous, there certainly is no laughter.
