**Core Concept**
Peroxisomes are organelles involved in the breakdown of fatty acids and amino acids, producing hydrogen peroxide as a byproduct. To mitigate oxidative damage, peroxisomes contain free radical scavengers that neutralize reactive oxygen species.

**Why the Correct Answer is Right**
The correct answer is a peroxisomal free radical scavenger, specifically catalase (CAT), which converts hydrogen peroxide (H2O2) to water and oxygen. This enzyme is crucial in maintaining the balance of reactive oxygen species within the cell. Catalase is localized in peroxisomes, where it is strategically positioned to neutralize the hydrogen peroxide produced during fatty acid oxidation.

**Why Each Wrong Option is Incorrect**
**Option A:** Glutathione peroxidase is indeed a free radical scavenger, but it is primarily found in the cytosol and mitochondria, not in peroxisomes.
**Option B:** Superoxide dismutase is an enzyme that converts superoxide anions to hydrogen peroxide, which would then be neutralized by catalase. However, it is not a peroxisomal enzyme itself.
**Option C:** NADPH oxidase is an enzyme that generates superoxide anions, contributing to oxidative stress, rather than scavenging free radicals.

**Clinical Pearl / High-Yield Fact**
Catalase is an essential enzyme for maintaining redox balance in peroxisomes. Its dysfunction has been linked to various diseases, including Alzheimer's disease and Parkinson's disease, where mitochondrial and peroxisomal dysfunction are implicated.

**Correct Answer:** C. Catalase.