Final answer:
The collapse of the Soviet Union was influenced by the success of anti-communist revolutions in Eastern Europe, leading to the overthrow of Gorbachev's government.
Step-by-step explanation:
The event that best completes the timeline to show the sequence of events in the collapse of the Soviet Union is option A, which states that the success of anti-communist revolutions in Eastern Europe leads to an overthrow of Gorbachev's government.
This event is significant because the fall of communist regimes in Eastern Europe, such as the Berlin Wall coming down in 1989, weakened the position of the Soviet Union and its leader, Gorbachev. The push for democracy and independence in Eastern Europe inspired similar movements within the Soviet Union itself, leading to the collapse of the Soviet Union in 1991.
Therefore, option A best completes the timeline to show the sequence of events in the collapse of the Soviet Union.
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