Im pretty sure its d m and c
Soldiers also made dugouts and funk holes in the side of the trenches to give them some protection from the weather and enemy fire. The front-line trenches were also protected by barbed-wire entanglements and machine-gun posts. Short trenches called saps were dug from the front-trench into No-Man's Land.
I would go with C cause its the only one that would go along the lines of buying or selling
The correct answer between all the choices given is the second choice or letter B. I am hoping that this answer has satisfied your query and it will be able to help you in your endeavor, and if you would like, feel free to ask another question.