The correct answer is:
A. The creation of the European Union.
The Russian Revolution, which toppled the Tsarist autocracy and lead to the emergence of the Soviet Union, developed in 1917.
The Cold War began in 1946 and ended between the Revolutions of 1989 and the 1991 collapse of the USSR, which finished communism in Eastern Europe.
The European Community (EC), was created in 1967 but in 1992, when the Community members agreed on further cooperation, it was renamed the European Union (EU).