Which statement is TRUE concerning a fire in a machinery space?

Correct Answer: Option D — the fixed carbon dioxide system should be used only when all other means of extinguishment have failed

Fixed CO2 systems are considered a last resort for machinery spaces because they are total-flooding agents that displace oxygen, rendering the space immediately lethal to personnel. Per USCG firefighting doctrine, manual suppression methods must be exhausted first to avoid unnecessary activation of the fixed system and potential re-flash hazards.