Which gas promotes combustion in flammable materials?

Oxygen is essential for combustion because it acts as an oxidizer in the combustion process. When a flammable material is exposed to sufficient heat and oxygen, a chemical reaction occurs that produces fire. This reaction typically entails the flammable material reacting with oxygen to release heat and light, which is the flame.

In contrast, carbon dioxide and argon are inert gases and do not support combustion; they lack the reactive properties needed to sustain the combustion process. Nitrogen, while present in the atmosphere, does not promote combustion either, as it does not actively participate in the chemical reactions necessary for fire. Oxygen, on the other hand, is the primary gaseous component required to maintain and accelerate the combustion of flammable materials, which is why it is the correct response to the question.