Final answer:
The correct answer is option b. European nations and World War II.
Step-by-step explanation:
According to the perspectives of President Franklin D. Roosevelt during his tenure, the future of the United States was deeply intertwined with European nations and the events of World War II.
Roosevelt entered into an alliance with key European figures such as British Prime Minister Winston Churchill and Soviet Premier Joseph Stalin to defeat Nazi Germany, which was viewed as the greatest threat to democracy and freedom.
After the conflict, the US sought to influence global politics by supporting or installing democratic governments and free-market economies in Europe, as well as extending its reach through alliances in Asia, Africa, and Latin America. Global involvement and postwar diplomacy became a cornerstone of US foreign policy, effectively marking the transition from isolationism to international engagement, laying the groundwork for the ensuing Cold War.