Answer: The Industrial Revolution.
Explanation:
The industrial revolution fundamentally changed everyday life. People began to leave the rural areas of the country en masse and move to the cities. Cities are becoming centers of life and places where industrial plants are installed. A large number of people are moving to cities for better opportunities. The industrial revolution had its phases in the twentieth century as well, so that process continued in that period. Thus, the economic factors of this phenomenon are in the background.
The answer to your question is the Ku Klux Klan
The Indian Removal Act of 1830 implemented the federal government's policy towards the Indian populations, which called for moving Native American tribes living east of the Mississippi River to lands west of the river.
So, to find out what IS a cause of the war we need to know M.A.I.N. That means Militarism, alliances, imperialism, and nationalism. That would mean the choices that aren't causes are totalitarianism, defense, and industrialism.