A fuel tank is considered to be gas free when the tank is __________.

Correct Answer: Option B — free of all dangerous concentrations of flammable or toxic gases

Gas-free status, as defined by NFPA and marine safety standards, requires the atmosphere to be free of toxic, flammable, or oxygen-deficient gases. This ensures the space is safe for personnel entry or hot work, eliminating dangerous concentrations that could lead to fire, explosion, or asphyxiation hazards.