In a fixed carbon dioxide extinguishing system for a machinery space, designed WITH a stop valve in the line leading to the protected space, the flow of CO2 is established by actuating __________.

Correct Answer: Option A — two controls

Systems equipped with a main line stop valve require a redundant actuation sequence per 46 CFR. Operators must utilize two distinct controls: one to open the stop valve and a separate control to release the CO2 from the cylinders.