Final answer:
The Soviet Union and the Warsaw Pact violently crushed a democratic movement in Eastern Europe known as the Hungarian Uprising.
Step-by-step explanation:
The correct answer to your question is a. Hungarian Uprising.
In 1956, Hungary experienced a national uprising known as the Hungarian Revolution of 1956. Thousands of Hungarians revolted against the communist government and called for democratic reforms and freedom from Soviet control. However, the Soviet Union and the Warsaw Pact, a military alliance between the Soviet Union and the Communist nations of Eastern Europe, violently crushed the uprising, removed the upstart Hungarian government, and reinstalled a Communist regime aligned with the Soviet Union.
After just ten days, Soviet forces entered Hungary, overpowered the interim government, and imposed a pro-Soviet government. Thousands of Hungarians were killed, many were imprisoned, and many more fled the country. This event served as a warning for other Eastern European nations that sought independence.