How is pressurization controlled in an aircraft?

Pressurization in an aircraft is primarily controlled by regulating the outflow of air from the cabin. The purpose of pressurization is to maintain a cabin altitude that is safe and comfortable for passengers and crew, especially at high altitudes where outside atmospheric pressure is significantly reduced.

The cabin pressure is managed through a system that controls how much air is allowed to exit the aircraft, which in turn affects the pressure inside the cabin. When the aircraft climbs, the outflow of air is controlled to keep the cabin pressurized, and when descending, the system can allow excess air to escape to maintain the desired pressure level. This regulation of outflow is crucial for ensuring that the cabin pressure remains at a suitable level throughout the flight.

Other options provided, such as increasing fuel flow, adjusting cabin heating, or monitoring cabin humidity, do not directly affect the pressurization system. Fuel flow is related to engine performance, cabin heating pertains to temperature management, and humidity monitoring relates to comfort but does not influence cabin pressurization directly.