Final answer:
The purpose of the United Nations is to maintain peace and security, promote human rights, and develop friendly relationships among nations. One scenario that could be a threat to U.S. national security is a leader from a terrorist organization sending members to a nearby country.
Step-by-step explanation:
The purpose of the United Nations is to maintain international peace and security, promote human rights and social progress, and develop friendly relationships among nations. Its main mission is to keep the peace by enhancing transparency, resolving disputes peacefully, and addressing the causes of conflict. It has tools such as sending peacekeepers to conflict zones and engaging in projects aimed at alleviating conflict.
A scenario that could be a threat to U.S. national security is b) a leader from a terrorist organization sending members to a nearby country like Cuba. Terrorism poses a direct threat to the security of nations, including the United States. It is important for countries to work together and take necessary measures to counter terrorism.