Which of the following is a part of the preflight safety check of the lavatory?

The correct answer is ensuring all placards are in good condition. During a preflight safety check, it is critical to verify that all safety-related information is properly displayed and in good condition in the lavatory. This includes signs and placards that direct passengers on the proper use of the lavatory facilities, emergency procedures, and safety reminders. Keeping these placards intact and legible helps ensure that passengers can access important safety information during the flight.

The other options pertain to different aspects of aircraft safety checks. Checking seatbelts is relevant to passenger seating areas, not lavatories. Testing cabin pressure is a procedure related to the overall cabin environment rather than specific to lavatories. Checking emergency exits is essential for ensuring that evacuation routes are accessible, which is also unrelated to the lavatory check. Each of these activities addresses important safety measures, but only the condition of placards specifically pertains to the lavatory's preflight safety check.