What is considered a capability that commanders must deploy as a single entity?

The correct answer is that a deployment echelon is considered a capability that commanders must deploy as a single entity. A deployment echelon refers to a military unit or a group of supporting elements organized to deploy together in a coordinated manner. This ensures that all necessary resources, personnel, and equipment are available at the same time and place, effectively enhancing operational efficiency during the deployment phase.

By deploying as a single entity, commanders can maintain better control over the operations and ensure that the unit can fulfill its mission upon arrival at the destination. This structured approach allows for strategic planning and execution, making it easier to monitor readiness and respond to any challenges that may arise during the deployment process.

Other options do not fit this definition as effectively. For instance, a task order is typically an instruction or direction for a specific task but does not represent a cohesive unit. A resource package consists of various elements necessary for operations but may not be deployed together as a single cohesive entity. Operational readiness is more about the preparedness of a unit or system rather than the actual act of deploying as a singular unit. Therefore, the definition and operational context of a deployment echelon align most closely with the notion of being a single entity during deployment.