**Core Concept:** Polymerization is a chemical process that occurs during the synthesis of polymers, which are large molecules composed of repeating units. The process involves the formation of covalent bonds between these units, leading to the formation of long chains. In some cases, it is undesirable for polymerization to occur during storage, and hence additives are used to inhibit or control this process.

**Why the Correct Answer is Right:** The correct answer, **D**: **Antioxidants**, is used to prevent polymerization during storage. Antioxidants are substances that inhibit oxidation reactions in a system. In the context of polymers, they help to scavenge free radicals that can initiate the polymerization process. By doing so, antioxidants prevent the formation of long polymer chains, thus keeping the polymer in the desired monomeric state when stored.

**Why Each Wrong Option is Incorrect:**

A. **Viscosity Modifiers**: These substances are used to alter the viscosity of a polymer solution or dispersion. They do not have any role in preventing polymerization during storage.

B. **Light Stabilizers**: Used to protect polymers from degradation caused by light exposure. They do not prevent polymerization.

C. **Oxidation Inhibitors**: These substances are added to inhibit oxidation reactions in a system. Similarly to viscosity modifiers, they do not prevent polymerization.

**Clinical Pearl / High-Yield Fact:** Polymerization inhibitors are essential in the pharmaceutical industry when handling polymers. By preventing the unwanted formation of long polymer chains during storage, these additives ensure that the polymer maintains its desired monomeric structure, which is crucial for the proper functioning of drugs, coatings, and other applications involving polymers.