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 faced severe problems due to inefficiency, corruption, and a lack of innovation. Additionally, the arms race with the United States during the Cold War put a tremendous strain on the economy. Ultimately, it led to the collapse of the Soviet Union in 1991.
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