Cartridge-operated dry chemical extinguishers used on MODU's should have the propellant cartridge weighed every __________.

Correct Answer: Option C — 12 months

46 CFR 109.209 requires that propellant cartridges for dry chemical extinguishers on MODUs be weighed annually. This maintenance interval ensures that the propellant charge has not leaked, guaranteeing that the extinguisher will function correctly under pressure when needed for emergency fire-fighting operations on the rig.