What is the main function of a cabin on an aircraft?

The primary function of a cabin on an aircraft is to provide space for passengers and their belongings. The cabin is designed to ensure comfort and safety for travelers during flight. It includes seating areas, overhead storage compartments for luggage, and amenities to support passenger needs, such as restrooms and service areas. This design prioritizes the passenger experience, making it essential for commercial aviation operations, where accommodating passengers and their carry-on items is crucial. The other options relate to different aircraft functions; air traffic control communications occur elsewhere, maintenance operations are conducted in dedicated spaces, and cockpit instruments reside in the flight deck, not the cabin.