According to the Marine Corps' mission, Marines are organized to be a?

The mission of the Marine Corps emphasizes its role as a "force in readiness." This means that Marines are prepared to respond quickly and effectively to a variety of crises and conflicts, maintaining a posture that allows them to deploy rapidly to any location around the world. This readiness encompasses not only combat capabilities but also the ability to provide assistance in humanitarian missions, disaster relief, and other operations that may arise.

Being a force in readiness highlights the Marine Corps' unique role as an elite fighting force that combines speed, agility, and versatility. It reflects the Corps' commitment to being prepared for any operation, whether it requires full-scale military engagement or support operations. The training and organization of Marines are designed specifically to enable them to act swiftly and effectively, which aligns with their foundational mission.

The other options focus on specific aspects of military operations or support roles but do not capture the overall intent of the Marine Corps’ mission, which centers on its readiness to respond to any situation that may arise.