What is powered by the "Avionics 2" bus?

The "Avionics 2" bus is typically responsible for powering specific avionics equipment within the aircraft's electrical system. In many aircraft, the marker beacon function, which includes receiving signals from ground stations to indicate the proximity to a runway or approach path, can be allocated to the avionics buses. Therefore, the marker beacon being powered by the "Avionics 2" bus is consistent with standard aircraft design where critical navigational and communication systems are distributed across different electrical buses for redundancy and reliability.

In this context, other items such as COM 1, pitot heat, and fuel pumps generally receive power from dedicated systems or separate buses. COM 1 might run off a primary communication bus, pitot heat could be powered directly from the electrical system without being specifically routed through an avionics bus, and fuel pumps usually have their power sources to ensure that they operate independently of avionics systems for safety and operational reliability. Thus, marker beacon functionality aligns with how various buses manage different systems in an aircraft, making it the correct answer.