Final answer:
In chemical reactions, the process associated with the reduction of a substance is reduction. Combustion reactions involve oxidation, not reduction.
Step-by-step explanation:
The process associated with the reduction of a substance in chemical reactions is c) Reduction. Reduction is the removal of oxygen from a substance, or the gain of hydrogen atoms. During a combustion reaction, which is a reaction where a substance reacts with oxygen, releasing energy in the form of light and heat, oxidation occurs rather than reduction.
In the context of redox (oxidation-reduction) reactions, the term oxidized refers to a substance that loses electrons, whereas reduced refers to one that gains electrons.