The main cause was the Stock Market Crash of 1929.
The correct answer is - 2.) Communist governments under Soviet control.
The Soviet Union, just like the United States, during the Cold War period tried to have as many allies as possible in order to have stronger support and protect its interests. Eastern Europe was a region that was almost totally under the control of the Soviets, apart from Yugoslavia which was strong on its own and didn't wanted to be submissive to other country.
The Soviets sponsored Communist governments and gave them a lot of support, be it financial, propaganda, or even military one if there were problems in the country. That led to almost all of the Eastern European nations having governments that were under the influence and control of the Soviets, making them a satellite countries to the Soviet Union.
Strong because I mean she is a queen
Answer: Primary Sources are immediate, first-hand accounts of a topic, from people who had a direct connection with it. Primary sources can include: Texts of laws and other original documents. Newspaper reports, by reporters who witnessed an event or who quote people who did.