Final answer:
In redox reactions, electrons are transferred between substances, with the losing substance being oxidized and the gaining one being reduced. Oxidation and reduction always occur together in these reactions, which are collectively known as redox reactions.
Step-by-step explanation:
During redox reactions, C. electrons are lost from one substance and added to another substance. The process in which electrons are lost is known as oxidation, and the process in which electrons are gained is referred to as reduction. Oxidation and reduction always occur together; thus, these reactions are collectively called oxidation-reduction or redox reactions. The species that is oxidized loses electrons and acts as a reducing agent, while the species that is reduced gains electrons and acts as an oxidizing agent.