On a MODU, a CO2 extinguisher is checked by __________.

Correct Answer: Option D — weighing the extinguisher

CO2 extinguishers are pressurized vessels that do not utilize pressure gauges for charge verification. Per 46 CFR 108.495, the only reliable method to determine if a CO2 extinguisher has lost its charge is by weighing the cylinder and comparing the result to the stamped tare weight on the valve.