Identify the incorrect reason for disintegration of USSR.
A. The Soviet economy used much of its resources in maintaining a nuclear and military arsenal.
B. The Soviet Union had become stagnant in an administrative and political sense.
C. Gorbachev reforms were a success and led to change of power in country.
D. Crisis situation in USSR after the Cold War.

C

Gorbachev carried out his reforms and loosened the system, he set in motion forces and expectations that could not be fulfilled which finally led to disintegration of USSR. Thus, Option C is incorrect.