What were the effects of the crisis of 1929 in Germany?

I- The crisis had a multifactorial and complex origin.
II- The crisis started in 1930 in Germany.
III- The crisis caused the collapse of the German economy and society.
IV- The crisis generated deflationary measures that led to increasing unemployment.
a) I and II are correct.
b) II and III are correct.
c) I, III, and IV are correct.