Why does NATO continue to exist after the Cold War ended?

A. NATO today is the government of the unified nation-state of Europe
B. NATO has become more of a broad supranational organization
C. NATO has become a global organization focused on fighting poverty
C. NATO today is an economic organization that created a universal currency for all of Europe

B. NATO has become more of a broad supranational organization.

After the Cold War, NATO's mission and focus shifted from solely countering the Soviet Union to broader security challenges. It transformed into a broader supranational organization aimed at promoting collective defense, peacekeeping, crisis management, and cooperation among its member states. The alliance expanded its partnerships and collaborations with non-member countries and organizations to address emerging global security threats and promote stability in different parts of the world.