What is the opposite of OIL in oxidation/reduction reactions?

In oxidation/reduction reactions, the acronym OIL stands for "Oxidation Is Loss," referring to the process where a substance loses electrons. The opposite of this process, which involves a gain of electrons, is correctly described by the phrase associated with reduction. Therefore, "Reduction Is Gaining" directly captures this concept, meaning that in a reduction process, an electron is gained by the species undergoing reduction.

Understanding these terms is crucial for grasping the fundamental principles of oxidation and reduction in chemistry. In this context, the correct choice emphasizes that when a substance is reduced, it acquires electrons, contrasting with the loss of electrons that occurs during oxidation.