Where is the APU located on the C-5 aircraft?

The Auxiliary Power Unit (APU) on the C-5 aircraft is located in the rear fuselage section. This placement is strategic as it allows for efficient access to the aircraft's electrical and pneumatic systems, which the APU powers. The rear location also helps keep the APU separate from the primary engines, minimizing noise and vibration in the cockpit and passenger areas. This design choice maximizes space and ensures that the APU can effectively provide power for ground operations without interfering with other aircraft systems. The other locations listed would not provide the same advantages in terms of access, safety, and functionality.