What are the three major components of the MK 25 Mod 2?

• A. electronic control unit, power management, and display panel.
• B. cooling system, filtration system, and telemetry module.
• C. pneumatic system, recirculation system, and the equipment case/harness subsystem.
• D. propulsion system, ballast system, and hull interface.

Answer: (C)

Understanding how the MK 25 Mod 2 organizes its life-support hardware reveals the three main functional blocks that make it work: the pneumatic system, the recirculation system, and the equipment case/harness subsystem.

The pneumatic system is focused on gas management. It handles the supply of breathing gas, regulates pressure, and controls the flow of gas into the breathing loop. This is the part you’d check if the gas isn’t delivering properly or if pressure/flow needs adjustment.

The recirculation system is the loop itself. It moves gas around the breathing circuit and includes the components that scrub CO2 and maintain the gas composition. This is essential for keeping the diver’s breathing gas breathable over time and under varying workload.

The equipment case/harness subsystem provides the physical housing and mounting framework. It protects, supports, and secures all the components to the diver, making the system portable, accessible, and stable in the water.

Other options describe electronics, cooling or telemetry, or completely different systems like propulsion or ballast, which aren’t the primary structural blocks of the MK 25 Mod 2.