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
Both are used during the process of synthesizing evidence.
The Declaration summarized the colonists’ motivations for seeking independence. By declaring themselves an independent nation, the American colonists were able to confirm an official alliance with the Government of France and obtain French assistance in the war against Great Britain. So basically so it could be official
C. It let to the mass migration of the Indian elite.