Why did Gorbachev fail to break up the Communist power monopoly in the Soviet Un

Why did Gorbachev fail to break up the Communist power monopoly in the Soviet Union?

A) Attempting to keep pace with tiger economies like Japan, Gorbachev overstretched the U.S.S.R.’s financial base.
B) Gorbachev failed to recognize the strength of Russian agricultural lobbyists.
C) Gorbachev’s attempts to match American industrial power overstretched the Soviet’s already crumbling economic base.
D) Gorbachev underestimated how brittle the Soviet power system was, and in turn, it collapsed.

This is for my political science class.