On a MODU, CO2 extinguishers must be weighed __________.

Correct Answer: Option D — annually

Per 46 CFR 109.209, CO2 cylinders on MODUs must be weighed annually to ensure the charge remains within the required weight tolerance. If the weight loss exceeds 10 percent of the stamped capacity, the cylinder must be recharged or replaced to maintain operational readiness for fire suppression.