Answer:
A. B. D.
Explanation:
The major reasons why the U.S was involved was because german unrestricted submarine warfare destroyed allied ships carrying american passengers.
I believe it is B because mining tons were very popular therefore overcrowded
The Berlin Airlift caused tensions to increase due to American airplanes transporting goods to democratic and West Berlin while East Berlin was owned by communist USSR.
C I would ask anyone for good advice on this