The chemical process involved in the combustion reaction is

Combustion is a process involving oxidation, reduction, and liberation of heat.

Combustion is a high-temperature exothermic (heat-releasing) redox (oxygen-adding) chemical reaction between a fuel and an oxidant, usually, atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke.

Hence the correct answer is (C) Redox reaction.