What items are located at each passenger service unit (PSU)?

The correct answer identifies the items typically found at a passenger service unit (PSU), which includes reading lights, air vents, and flight attendant (FA) call buttons. The reading lights are adjustable lights that provide passengers with the ability to read comfortably during the flight. The air vents allow passengers to control airflow for their personal comfort. The flight attendant call buttons are crucial for passenger communication with cabin crew, allowing them to request assistance or service when needed.

In contrast, other options include items that are not standard features at the PSU. Oxygen masks, while vital for safety, are typically housed in compartments overhead rather than at the PSU itself. Snack compartments are also not part of the PSU; instead, they are typically part of the galley where food and beverages are stored and prepared for service. Thus, option B accurately reflects the primary functions and features integrated into each passenger service unit.