Operation of the valve control release on a fixed CO2 system must immediately __________.

Correct Answer: Option B — secure all mechanical ventilation in the protected space

In accordance with 46 CFR 108.439, operating the valve control release mechanism on a fixed carbon dioxide system must automatically and immediately shut down all mechanical ventilation serving the protected compartment. Stopping ventilation prevents the loss of the CO2 extinguishing concentration and halts forced air from feeding the fire.