Which of the following is a key function of the cabin pressurization system?

The primary role of the cabin pressurization system is to ensure that the cabin altitude remains lower than the aircraft altitude, thereby providing a safe and comfortable environment for passengers and crew during flight. As an aircraft ascends, the external atmospheric pressure decreases significantly, which can lead to hypoxia—a condition caused by insufficient oxygen available at higher altitudes.

To counteract this effect, the pressurization system adds air to the cabin to keep the pressure and, consequently, the oxygen levels at safe operational standards. By maintaining a lower cabin altitude than the actual altitude of the aircraft, the system allows occupants to breathe comfortably without the negative effects associated with high-altitude flying. This is crucial for the safety and health of everyone onboard, making it a fundamental function of any aircraft's design.

While controlling cabin noise, humidity, and temperature are important aspects of cabin comfort, they are not the primary functions of the cabin pressurization system itself.