It would be A or D depending.
A if you are talking about the 1910's-20's. The war lead to some rapid growth in the military and made the USA into the central hub of trade in west as many nations were indebted to them.
D as this was the first time the USA became the global power as they took control of Cuba, Guam and the Philippines in this time.
B)it made the south far richer than the north
