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

46 CFR requires bilge systems to prevent accidental flooding. Stop-check valves in bilge suction manifolds ensure that if a valve is left open, water cannot flow from the sea or other compartments back into the bilge, providing a critical barrier against progressive flooding.