Oxidation is donating electrons.

• A. Gaining electrons
• B. Losing electrons
• C. Donating electrons
• D. Absorbing protons

Answer: (C)

Oxidation involves the loss of electrons. When a molecule donates electrons, it is giving up negative charge, which is exactly what happens during oxidation. In biology this is seen when NADH donates electrons and is oxidized to NAD+, with the electrons moving to another molecule that becomes reduced. So describing oxidation as donating electrons captures the direction of electron flow away from the oxidized substance.

Gaining electrons describes reduction, not oxidation, and absorbing protons is not part of the redox concept.