Where is the RA/BA pushbutton used to select the radar altimeter scale located?

The RA/BA pushbutton used to select the radar altimeter scale is located on the automatic flight control system panel. This positioning is critical because the automatic flight control system (AFCS) often integrates various altitude management features. The RA (radar altimeter) provides real-time altitude information necessary for the system to maintain optimal flight conditions, especially during low-level flight approaches where precision is crucial.

Choosing this option over others is essential because multifunction displays and control panels serve broader purposes, such as displaying various flight data and consolidating controls, but they do not specifically focus on altitude management in the same specialized way that the AFCS panel does. The mission communication sensor switching panel is unrelated to altitude data management. Thus, the correct option effectively reflects where the function is most accessibly and logically embedded within the aircraft's systems.