Final answer:
The easiest MRC population to decrease for improving deployability rates is MRC C (Partially Ready), as these individuals often have issues that can be resolved more quickly and efficiently than those in more severe readiness categories.
Step-by-step explanation:
The MRC population that is the easiest to decrease for improvement of a unit's deployability rates is MRC C (Partially Ready). These are service members who might be facing a temporary condition affecting their readiness, such as a short-term injury or illness, minor administrative issues, or recently expired qualifications. Focusing on MRC C personnel allows for quicker transitions to higher readiness levels because their issues are typically more straightforward to resolve as compared to those of individuals in MRC D (Not Ready), who may be dealing with more complex, long-term medical conditions or other readiness barriers. To improve a unit's deployability rates, resources and strategies can be implemented to attend to the needs of those in the MRC C category by addressing their specific limitations and expediting their return to fully ready status.