How is cabin pressurization primarily controlled?

Cabin pressurization is primarily controlled by managing the outflow of air from the cabin, which is accomplished through the outflow valve. This valve allows excess pressure to escape from the cabin when the aircraft is gaining altitude, helping to maintain a safe and comfortable pressure level inside the cabin. As the aircraft ascends, the atmospheric pressure outside decreases, and to counteract this, the outflow valve can be opened, allowing some of the cabin air to vent out.

This regulation helps prevent the cabin pressure from exceeding safe limits and allows it to remain stable as the aircraft changes altitude. The correct functioning of the outflow valve is critical for effective pressurization control, ensuring that the cabin remains at a pressure that is comfortable for passengers and crew during flight.

While the other options mention components involved in the overall cabin environment or pressure management, they do not serve as the primary means of controlling cabin pressurization. The intake valve and compressor play supportive roles in the circulation and maintenance of air but are not directly responsible for pressure control in the same way that the outflow valve is. Cabin fans are mainly focused on air distribution rather than pressure management itself.