If the question is true or false, the answer is true.
The most important factor from the options that lead to radicalized political parties was The Great Depression of 1929 (C).
The Wall Street Crash of 1929 led to a chain reaction not only in the U.S. but in many European countries as well. In the worst moments of the period, 22 to 23% of the American workforce, and 44% of German's workforce didn't have a job.
Due to the crisis, many American creditors charged loans made throughout the world; American companies stopped investing in other countries.
This generalized crisis, unemployment, and increasing misery of the population created a fertile soil on which fascist and nazi political figures fed.
Answer:
Not 100 percent sure but I think it's C. I'm the moon.
Lack of political maturity & no executive power