Answer:
the use of poison gas and machine guns
Explanation:
Aerial attacks weren't really a thing, unrestricted submarine warfare was a reason why the US joined the war but not a factor in high casualty rates, and blimps using direct artillery fire isnt as practical as machine guns and poison gas
I believe it was Sickness of FDR. He had polio so A should be the answer
True, in order to make their mercantilist economy succeed Britain needed to import raw materials from its colonies
