Americans' fervent isolationism in the 1930s can best be attributed to

Americans' fervent isolationism in the 1930s can best be attributed to

a. their regrets about participating in WWI.

b. bitter memories of the ungrateful nations that defaulted on their WWI debts.

c. the totalizing impact of the Great Depression and the need to focus on getting out of it.

d. None of these

e. All of these

answer : e. All of these