In the 1930s, many people began thinking Marx was right and that Communism was the wave of the future because

Communism

Explanation:

Communism began to come to power after the overthrow of the Romanov Dynasty (Tzar Nicholas II). The reason Communism became popular in Europe because of its ideology of Karl Marx which requires common ownership of the means of production and a withering of the state. Many thought of Communism as the wave of the future because it attracted Eastern countries and Korea. The ideology promising to overturn the power of capital, and the misuses on society, attracted supporters.

uncle sam would be tossing and turning in his grave : *)

calvin taught his followers that human beings needed to follow strict rules to overcome their nature and do good. second choice