Final answer:
The fall of the Soviet economy in the 1980s was the ultimate undoing of the Soviet Union.
Step-by-step explanation:
The ultimate undoing of the Soviet Union was the fall of the Soviet economy in the 1980s. The Soviet economy was heavily centralized and inefficient, leading to a stagnation in economic growth. Additionally, the USSR had a massive military-industrial complex that was costly to maintain.
The combination of economic problems, high military expenditure, and a lack of innovation eventually led to the collapse of the Soviet Union.
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