Which statement about the IRU batteries is correct?

Each Inertial Reference Unit (IRU) in the C-17 has its own battery designed to provide power for up to 30 minutes. This is significant because it ensures that each IRU can maintain its navigational functions even in the event of a loss of primary power. The design allows for redundancy, enhancing the reliability of the IRUs during flight, which is critical for navigation and flight safety.

The other statements do not accurately reflect the operational capabilities of the IRUs. The IRUs do not share a single battery, nor do they depend solely on the aircraft's main battery in case of power failure, and backup power is indeed available to ensure continued operation during critical moments. Each IRU's independence in power sourcing is a crucial aspect of the aircraft's avionics reliability.