What is the function of a Passenger Service Unit (PSU) on an aircraft?

The function of a Passenger Service Unit (PSU) on an aircraft is primarily to provide oxygen and emergency equipment for passengers. In the event of cabin depressurization or another emergency, the PSU is designed to automatically deploy oxygen masks, ensuring that passengers have access to supplemental oxygen as needed. Additionally, the PSU often includes lights, and sometimes call buttons, that help facilitate communication between passengers and cabin crew. This setup is vital for passenger safety and ensures that all necessary emergency equipment is readily accessible, which aligns with regulatory safety standards. Other options, while related to passenger experience and comfort, do not define the specific purpose of a PSU as it is recognized in aviation safety.