Plese ? world history questions i do not understannd

(1)what is one way the eastern front was different from the western front?

a. the eastern front was fought with more military technology than the western front.
b. the western front provided the central powers with their most decisive victories.
c. the western front suffered more casualties than the eastern front.
d. the eastern front had front lines that moved widely, while the western front did not.

(2)what was the most significant effect of u-boat attacks on the fighting on land?

a. they killed many soldiers.
b. they kept soldiers from the front lines.
c. they destroyed vital supplies.
d. they created a stalemate.

(3)which new type of warfare was responsible for civilian and military deaths and was banned after the war?

a. poison gas
b. armored tanks
c. trench warfare
d. aerial ”dogfights”