I studied this a while back, the answer is B.
D it will be D because if you actually google the document and look for the number you will be sure to find the answer but its D anyway.
Answer:
The answer is trench warfare. This is a kind of land conflict using engaged fighting lines containing mainly of military channels, in which the troops are well sheltered from the opponent's small weapons fire and are considerably protected from weapon.
a type of combat in which opposing troops fight from trenches facing each other.
Explanation: