Which statement describes the nature of non-flammable gases?

The statement that non-flammable gases are incapable of sustaining combustion accurately reflects their inherent characteristics. Non-flammable gases, by definition, do not support the chemical processes necessary for fire to occur. This means that, even in the presence of an ignition source, these gases cannot continue to burn because they lack the properties required to react with oxygen in a way that produces and sustains combustion.

In contrast, options suggesting any capacity to ignite or support combustion, whether at high concentrations or lower temperatures, do not align with the fundamental understanding of non-flammable gases. These gases simply do not engage in combustion reactions, making the statement about their incapacity to sustain combustion the most definitive and accurate representation of their nature.