Final answer:
The primary Navy Reserve component for immediate manpower mobilization is the Naval Fleet Reserve. It provides a ready pool of trained personnel to support the Navy swiftly in times of need.
Step-by-step explanation:
The Navy's primary source for immediate manpower mobilization is associated with the Naval Fleet Reserve. This component is designed to be quickly activated to supplement the active-duty forces in times of need, serving as a ready pool of trained individuals who can provide various operational capabilities to the Navy on short notice. It is a critical element of the Navy Reserve, ensuring that the Navy can maintain a high state of readiness and fulfill its mission requirements.