Final answer:
The event that caused a change in political boundaries in 1990 was the collapse of the Soviet Union, which influenced the independence and restructuring of several nations in Eastern Europe.
Step-by-step explanation:
The event that prompted political boundaries to change in 1990 was c. The collapse of the Soviet Union. This led to significant political and geographical changes, especially in Europe. The dissolution of the Soviet Union resulted in the independence of 15 countries that were previously Soviet republics. Additionally, the collapse removed the iron grip that the Soviet Union had on Eastern Europe, leading to political changes and the redrawing of boundaries in that region.
Furthermore, this seismic shift in geopolitical power fundamentally restructured the international political landscape, transitioning from a bipolar world during the Cold War to a unipolar one, with the United States as the dominant superpower. Overall, the collapse of the Soviet Union led to a reconfiguration of political boundaries, impacting multiple nations and peoples.
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