Who served as President Ronald Reagan's national security advisor?

Colin Powell served as President Ronald Reagan's national security advisor, a role he held from 1987 to 1989. During this time, he was involved in shaping U.S. foreign policy and addressing various international issues, particularly towards the end of the Cold War. Powell's military background and strategic thinking were essential in advising Reagan on matters of defense and security.

Henry Kissinger, while a prominent figure in American foreign policy as Secretary of State and National Security Advisor under Nixon and Ford, was not involved in Reagan's administration. Andrew Young served as the U.S. ambassador to the United Nations during the Carter administration and is known for his work in civil rights and diplomacy, rather than national security under Reagan. Condoleezza Rice is most recognized for her roles in the Bush administration, particularly as national security advisor and Secretary of State, well after Reagan's presidency. Understanding these timelines and roles clarifies why Colin Powell is the correct answer in this context.