Where does the APU get fuel from?

The APU (Auxiliary Power Unit) typically receives fuel from the left collector tank. This is designed to ensure that the APU has a dedicated and reliable source of fuel to operate independently of the main engines, especially during ground operations or when the aircraft is not airborne. Utilizing the left collector tank helps maintain system efficiency and ensures that fuel can be accessed even if the main fuel system is not active.

The other options may seem plausible; however, they either pertain to the fuel systems of the main engines or suggest external sources that are not standard for APU operation during routine usage within the aircraft systems.