The removal of electrons from an atom or compound is called:

Explanation

The correct answer is oxidation. Oxidation involves the removal of electrons from an atom or compound, which results in an increase in its oxidation state. This process is often paired with reduction, where another species gains the electrons that were lost. The term "reduction" refers to the opposite process, where a molecule gains electrons. Oxidative phosphorylation, on the other hand, is a mechanism for ATP production in mitochondria, not directly related to electron removal. Finally, an oxidation-reduction reaction describes a full redox process where both oxidation and reduction occur, encompassing both electron loss and gain.