What must be checked at the AFT galley?

The correct choice emphasizes the importance of ensuring the operational readiness of essential emergency equipment like the Emergency Locator System (ELS) and the water supply system located in the AFT galley. Checking the ELS is critical because it is designed to assist in locating the aircraft in an emergency situation, while ensuring that the water system is functional contributes to the overall safety and comfort of passengers and crew during the flight.

In a safety-critical environment such as aviation, thorough checks of equipment and systems can directly affect the outcome of emergency procedures. The AFT galley is particularly significant as it is a central hub for crew operations and directly linked to passenger service. Therefore, maintaining these systems in proper working condition is paramount.

While the other options—cabin baggage, first aid kit, and newspaper supply—pertain to various aspects of cabin safety and service, they do not hold the same level of urgency and critical nature in terms of safety protocols as the ELS and water system do. The ELS and water systems have a direct impact on emergency response capabilities, making their checks vital during pre-flight preparations.