What should you check for as evidence of tampering in the lavatory?

When assessing for evidence of tampering in the lavatory, checking the smoke detector is crucial. Smoke detectors are important safety devices designed to alert crew and passengers to potential fire hazards. If someone has tampered with the smoke detector, it could mean that they have disabled it or altered its function, which poses a significant safety risk.

A functioning smoke detector is essential for the early detection of smoke or fire, and ensuring that it has not been tampered with helps maintain the integrity of the aircraft's safety systems. Monitoring for alterations to this crucial device can help ensure the safety of all onboard.

Other choices, such as cabin lights, water levels, and emergency exits, while important to the overall functioning of the aircraft, do not directly relate to evidence of tampering specific to fire safety protocols within a lavatory setting. Therefore, focusing on the smoke detector provides the most relevant information regarding potential tampering.