Final answer:
The EFIS Control Panel or the FMS Control Unit is typically used to select the NAV SRC for display on the PFD, allowing pilots to choose the navigation system to be used.
Step-by-step explanation:
The control panel used to select the NAV SRC (Navigation Source) for display on the Primary Flight Display (PFD) is commonly referred to as the EFIS Control Panel or the Flight Management System (FMS) Control Unit, depending on the aircraft make and model. The NAV SRC selection allows the pilot to choose between different navigation systems, such as GPS, VOR, or ILS, to be displayed on the PFD, providing critical navigation information during flight.