Final answer:
The Soviet Union's collapse in 1991 meant the end of its alliances, including the Warsaw Pact, as Eastern European countries sought independence and later built ties with Western Europe and institutions like the EU and NATO. So, the correct answer is option 2.
Step-by-step explanation:
The collapse of the Soviet Union in 1991 marked the end of its alliances with Eastern European countries and the Warsaw Pact. When the Warsaw Pact nations sought independence in the late 1980s, the Soviet Union, under Mikhail Gorbachev's leadership, was already struggling with internal challenges and thus could not maintain its hold over these nations.
Subsequently, the Pact and its influence dissolved alongside the Soviet state. Thus, upon the collapse of the Soviet Union, it did not negotiate new agreements with Eastern European countries; instead, those countries declared independence and searched for new paths forward, including economic ties with Western Europe and, for some, eventual membership in the European Union (EU) and the North Atlantic Treaty Organization (NATO).