Which type of ventilation is required for enclosed spaces containing gasoline, machinery, or fuel tanks? (small passenger vessel regulations)

Correct Answer: Option C — Natural supply and mechanical exhaust

46 CFR 25.40-1 requires that spaces containing gasoline machinery or fuel tanks utilize natural supply ventilation to bring in fresh air and mechanical exhaust ventilation to remove heavy fuel vapors. This combination ensures that explosive vapors are effectively cleared from the bilge and machinery space before engine ignition.