What feature does a cabin altitude warning system provide during an emergency?

The cabin altitude warning system is designed to alert the crew and passengers to dangerous cabin altitude conditions that could lead to hypoxia, which is a lack of sufficient oxygen reaching the body's tissues. In the event of a cabin altitude emergency, the system activates the automatic deployment of passenger oxygen masks. This feature is crucial because if the cabin altitude exceeds safe levels, the available oxygen may drop significantly, and the masks provide a supplemental oxygen source for passengers to breathe safely until the situation is stabilized or the aircraft descends to a safer altitude.

This proactive measure ensures the safety and well-being of everyone on board during critical situations, allowing for an immediate response to the loss of cabin pressure or an abnormal rise in altitude. Other features listed, such as deploying emergency exits, increasing cabin pressure, or shutting down all electrical systems, do not directly address the immediate need for supplemental oxygen during a loss of pressurization event.