What governmental body is responsible for advising the president on national security measures?

The National Security Council (NSC) is the governmental body responsible for advising the president on national security measures. It plays a crucial role in coordinating the administration's foreign and military policy as well as ensuring that the various agencies within the U.S. government work together effectively on issues related to national security. The NSC comprises key members including the president, vice president, and secretaries of state and defense, along with other officials who may be invited to participate in meetings based on the topic being discussed.

The other options, while significant in their roles, do not primarily focus on advising the president on national security. The Department of Defense is primarily responsible for military operations and ensuring national defense. The Central Intelligence Agency focuses on gathering and analyzing intelligence but does not directly advise on policy. The Federal Bureau of Investigation deals mainly with domestic security and law enforcement issues and does not operate at the same level of national security advisory as the NSC. The collective function of the NSC makes it the authoritative body for providing strategic advice on matters of national security directly to the president.