Which of the gases listed is the poisonous gas most likely to be found in a closed compartment involved in a fire?

Correct Answer: Option D — Carbon monoxide

Carbon monoxide is a byproduct of incomplete combustion, frequently generated during shipboard fires in enclosed compartments. It is highly toxic and colorless, posing a severe inhalation hazard to firefighting teams. Proper SCBA usage is mandatory when entering fire-affected spaces to prevent exposure to this lethal, odorless gas.