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

The function of a Passenger Service Unit (PSU) is to provide oxygen in emergencies. In aircraft, the PSU is located above the passenger seats and includes several key features, among which are the oxygen masks that drop down in the event of cabin depressurization. This is crucial for passenger safety, as it ensures that individuals have access to supplemental oxygen if the cabin becomes unpressurized.

While there are other important components on an aircraft, the options concerning the flight crew's communication devices, information displays, or passenger luggage do not belong to the scope of what a PSU handles. The PSU primarily focuses on delivering safety measures, particularly related to oxygen supply during emergency situations, making its role essential in ensuring passenger well-being during crises.