**Core Concept**
Refsum's disease is a rare genetic disorder characterized by the accumulation of a specific type of fatty acid called phytanic acid in the body. This accumulation leads to a range of systemic symptoms due to the toxic effects of phytanic acid on various tissues.

**Why the Correct Answer is Right**
The classic tetrad of Refsum's disease includes a combination of clinical features that are directly related to the toxic effects of phytanic acid on the nervous system, retina, and other tissues. The correct tetrad involves peripheral neuropathy, retinitis pigmentosa, cerebellar ataxia, and elevated levels of phytanic acid in the blood. The combination of these features is a hallmark of Refsum's disease and results from the impaired breakdown of phytanic acid due to mutations in the alpha-oxidation pathway.

**Why Each Wrong Option is Incorrect**
- **Option A:**
- **Option B:**
- **Option C:**

**Clinical Pearl / High-Yield Fact**
Refsum's disease is an example of a condition where a specific dietary intervention can help manage symptoms. Patients with Refsum's disease often benefit from a low-phytanic acid diet, which involves avoiding foods rich in phytanic acid, such as dairy products and processed meats.

**Correct Answer: C.**