I believe that the answer you are looking for is Mixed.
I believe, I'm not 100% sure.
The depression didn't reach the USSR because the USSR did not have a capitalist government. It also didn't have a stock exchange and didn't trade with any capitalist governments. The USSR was also very isolated because of communism.
The answers are:
17.B
18.C
19.B
20.A
hope this helps (: