What items are powered by the auxiliary battery bus?

The auxiliary battery bus is designed to provide power to essential systems in the event that the main electrical systems are lost or fail. This bus plays a crucial role in maintaining operation of critical items required for flight safety.

The standby instruments and the lighting for those instruments are essential for the pilot's ability to maintain situational awareness in case of primary power loss. These instruments ensure that the pilot has access to vital flight data.

The UHF transceiver and backup UHF control are similarly important. In scenarios where communication with other aircraft or ground control is necessary, having a backup system ensures that the pilot can still maintain crucial communications.

Moreover, the FIRE 1 fire warning system is fundamental for safety, as it alerts the crew to potential engine fires, allowing for prompt action.

Since all of these items are powered by the auxiliary battery bus in an emergency, the correct answer encompasses all of the described functionalities. Thus, it's accurate to state that they are all supported by this important backup system. This integrated approach not only underscores the redundancy built into the aircraft’s design but also ensures that pilots have access to critical information and systems when it matters most.