How does an inert gas system on a tanker function to prevent explosions in cargo tanks?

Correct Answer: Option D — Inert gas dilutes the flammable vapor and air concentrations to keep them below the lower explosive limit.

Inert gas systems prevent explosions by maintaining an atmosphere where the oxygen concentration is insufficient to support combustion. By diluting the hydrocarbon vapors and keeping the oxygen level below 8%, the mixture remains outside the flammable range, effectively preventing the ignition of vapors within the cargo tanks.