Which titles or directives describe the functions and composition of the Marine Corps?

The correct answer is based on the specific legal and regulatory framework that outlines the roles, missions, and organizational structure of the Marine Corps. Title 10 of the U.S. Code delineates the establishment and functions of the armed forces, including the Marine Corps, providing essential statutory authority for its operations, organization, and capabilities. It is fundamental for understanding the legal basis for Marine Corps operations.

DoD Directive 5100.1 complements Title 10 by providing detailed guidance on the organization of the Department of Defense and clarifying the responsibilities, authorities, and functions of the military services, including the Marines. This combination ensures that all aspects of the Marine Corps' operation within the context of national defense strategy are explicitly defined and understood.

Other options contain references to frameworks that do not specifically address the Marine Corps’ functions and composition. The National Security Act primarily revolves around the establishment of the Department of Defense and does not provide the specific details needed for the Marine Corps. Similarly, Army Regulations pertain to the Army specifically, while Department of Defense Handbook and Air Force Instructions are tailored to the functions and rules relevant to the Air Force, not the Marine Corps. Finally, Joint Publications and Navy Guidelines focus more on collaboration between services and naval operations rather than directly defining