Answer:
A. They were extremely precise and successful in every attack.
Explanation:
Depth charges are quite literally explosives in a barrel that sink to a set depth before exploding. They wouldn't be 100% accurate due to them tumbling as they went down into the water. You usually needed at least a couple of Depth charges before you could knock out a Jerry (slang word for German during world war 2, fun fact!) U-Boat submarine, and this still applies today.
C - He thought it would be easier than trying to conquer the territory.
A is incorrect as, at the time, the United States and France were allies and would not be going to war at any time during this time period.
B is incorrect as, well, how would this aid the French in a war with Britain? If France needed funds from an ally, they could do so.
D is incorrect as, well, the Louisiana Purchase had no access to the Caribbean or the sea much.
Hope this helps!