C because the rest of them are not valid
The coup was the culmination of a conflict between the old and new political, economic, and social orders that had been under way since Gorbachev had risen to power in 1985. His perestroika and glasnost reforms had set in motion forces that were bound to collide at some point.
Answer:
they help each other
Explanation:
they can be help each other and have their own solutions
