A cabinet or space containing the controls or valves for the fixed firefighting system must be __________.

Correct Answer: Option D — posted with instructions on the operation of the system

46 CFR 108.497 requires that any space or cabinet housing controls for a fixed fire-extinguishing system must be clearly posted with operating instructions. This ensures that any crew member, regardless of their specific training, can quickly and correctly activate the system during the high-stress environment of an emergency.