(A) ** muddy trenches
(B) the air
(C) deserts
(D) the lunch room
EXPLANATIONS BELOW
Concept note-1: -The majority of the fighting took place in Europe along two fronts: the western front and the eastern front. The western front was a long line of trenches that ran from the coast of Belgium to Switzerland.
Concept note-2: -Trenches were common throughout the Western Front. Trench warfare in World War I was employed primarily on the Western Front, an area of northern France and Belgium that saw combat between German troops and Allied forces from France, Great Britain and, later, the United States.
Concept note-3: -Trench warfare is a type of combat in which the opposing sides attack, counterattack, and defend from relatively permanent systems of trenches dug into the ground.
Concept note-4: -Much of the land where the trenches were dug was either clay or sand. The water could not pass through the clay and because the sand was on top, the trenches became waterlogged when it rained. The trenches were hard to dig and kept on collapsing in the waterlogged sand.