B because after the Bolshevik revolution, there was a civil war between the Bolsheviks and the White Movement (and some other minor factions like anarchist Ukraine and the green peasant armies)
I think the term that best applies to it is historical materialism. It focuses on the dialectics of understanding history using contradictions in politics, economy, culture and social changes inside a society. These cause the development and changes to further improve and have another society that would cater the people's interest.
The Cold War was a state of geopolitical tension after World War II between powers in the Eastern Bloc and powers in the Western Bloc. Historians do not fully agree on the dates, but a common timeframe is the period between 1947, the year the Truman Doctrine was announced, and 1991, the year the Soviet Union collapsed. If you want to make sure this is the right answer for to the link below hope this helps on what ur looking for.http://www.history.com/topics/cold-war/cold-war-history
Checks and balances. Each branch “checks” the power of the other branches to make sure that the power is balanced between them.
