Accidental flooding of the engine room bilges through the bilge system is prevented by __________.

Correct Answer: Option D — stop-check valves installed in the bilge suction manifolds

Stop-check valves in bilge suction manifolds prevent backflow from the sea or other tanks into the bilges. By allowing flow only in the direction of the pump, these valves provide a critical safety barrier against accidental flooding, as mandated by 46 CFR requirements for bilge piping systems.