Where are autopilot guidance modes selected on the A320?

Autopilot guidance modes on the A320 are primarily selected using the Flight Control Unit (FCU) and the Multi-function Control Display Unit (MCDU). The FCU is located on the overhead panel and provides the pilots with manual controls for various autopilot functions such as selecting altitude, vertical speed, and flight mode (like HDG, NAV, etc.).

The MCDU is also instrumental in programming the flight management system, which works alongside the autopilot functions. It allows pilots to input and modify flight plans, which is crucial for the autopilot to effectively manage the aircraft's flight path. Thus, the combination of the FCU for immediate control and the MCDU for flight path management makes this the correct and most suitable answer.

Other options refer to components related to flight management and display but do not accurately represent where the autopilot guidance modes are selected. For instance, while the EFIS control panel is part of the cockpit instrumentation, it does not actually allow for the selection of autopilot modes. Similarly, ADIRUs are part of the aircraft's inertial reference systems, which provide navigation data but do not involve the selection of autopilot modes. Therefore, the FCU's role in direct autopilot mode selection