**Core Concept**
Catalase is an enzyme that catalyzes the decomposition of hydrogen peroxide into water and oxygen. This reaction is crucial for maintaining cellular homeostasis and preventing oxidative damage. Hydrogen peroxide is a reactive oxygen species (ROS) that can cause cellular damage if not properly managed.

**Why the Correct Answer is Right**
Catalase (EC 1.11.1.6) is a heme-containing enzyme that catalyzes the conversion of hydrogen peroxide (H2O2) to water (H2O) and oxygen (O2). This reaction is a key defense mechanism against oxidative stress, allowing cells to detoxify hydrogen peroxide and maintain a stable redox environment. The enzyme acts by donating an electron to the hydrogen peroxide molecule, resulting in the formation of water and oxygen.

**Why Each Wrong Option is Incorrect**
**Option A:** Superoxide dismutase is an enzyme that catalyzes the conversion of superoxide (O2-) to hydrogen peroxide and oxygen, not the reverse reaction catalyzed by catalase.

**Option C:** Glutathione peroxidase is an enzyme that reduces lipid hydroperoxides and hydrogen peroxide to their corresponding alcohols, using glutathione as a reducing agent. While it does work on hydrogen peroxide, its primary function is different from that of catalase.

**Option D:** Myeloperoxidase is an enzyme that produces hypochlorous acid from hydrogen peroxide and chloride ions, which is involved in the antimicrobial activity of neutrophils. This is a different reaction from the one catalyzed by catalase.

**Clinical Pearl / High-Yield Fact**
Catalase is a key enzyme in maintaining cellular homeostasis and preventing oxidative damage. Its deficiency or dysfunction can lead to increased levels of hydrogen peroxide, contributing to various diseases, including cancer, neurodegenerative disorders, and atherosclerosis.

**✓ Correct Answer: B. Catalase**