Answer:
c. Capitalism
d. The U.S. remained neutral
Step-by-step explanation:
Capitalism is a system where the owner keeps the profit from the workers job, in this case the profits go to the business owner and the worker gets a fixed payment for his work done.
Isolationism was a political current after WWI and during the great depression era, where the government of the United States avoided being involved in armed conflicts in the other continents, however in America they did protected their interests in south and central america, sending troops and support.