Each inert gas system must be designed to supply the cargo tanks with a gas, or mixture of gasses, that has an oxygen content by volume of __________.

Correct Answer: Option C — 5% or less

Under 46 CFR 32.53-10 and SOLAS Chapter II-2, an inert gas system must deliver gas with an oxygen content of 5% or less by volume to the cargo tanks. This maintains the atmosphere well below the limit required to support combustion.