Final answer:
Navigation frequencies in aircraft can be preset using the Flight Management System (FMS), Control Display Unit (CDU), NAV RADIOS page, or Radio Management Panel, which are critical for managing in-flight navigation and communication tasks.
Step-by-step explanation:
The question refers to the systems onboard an aircraft used for navigation and communication. The correct answer is that navigation frequencies may be preset via the FMS (Flight Management System), CDU (Control Display Unit), NAV RADIOS page, or the Radio Management Panel. These interfaces allow pilots to manage the aircraft's navigation and communication radios, including tuning to the appropriate frequencies for their flight plan before departure or during the flight as needed. For example, the FMS is a multifunctional device that automates a wide variety of in-flight tasks, and its keypad and screen can be used to input and manage frequencies.