Respuesta :
The best example of America's adoption of isolationism in the post-WWI and Great Depression of the 1930s was the refusal to ally with other nations.
What is Isolationism?
This refers to a policy that was issued for a country to stay isolated without collaboration or trade exchange with other countries.
America, during the 1930s, pursued an Isolationist policy which made it avoid alliances with other nations.
The correct answer, thus, is C.
See the link below for more about Isolationism:
https://brainly.com/question/791540