**Core Concept**
Hepatolenticular degeneration, also known as Wilson's disease, is a genetic disorder characterized by excessive accumulation of a heavy metal in the body, leading to damage in the liver, brain, and other organs. This condition is caused by a defect in the ATP7B gene, which plays a crucial role in copper transport and metabolism.

**Why the Correct Answer is Right**
In Wilson's disease, the accumulation of copper in the liver and brain leads to cellular damage and oxidative stress. The correct answer is associated with the deposition of copper in these organs, causing the characteristic symptoms of the disease. The ATP7B protein is responsible for exporting excess copper into the bile, where it can be excreted. In Wilson's disease, mutations in the ATP7B gene lead to impaired copper export, resulting in its accumulation in the liver and brain.

**Why Each Wrong Option is Incorrect**
**Option A:** Iron is not associated with hepatolenticular degeneration, as this condition is specifically related to copper accumulation.
**Option B:** Manganese is another heavy metal that can cause neurological symptoms, but it is not the primary metal involved in Wilson's disease.
**Option C:** Zinc is an essential mineral that plays a crucial role in many biological processes, but it is not directly involved in the pathophysiology of Wilson's disease.

**Clinical Pearl / High-Yield Fact**
Wilson's disease is an autosomal recessive disorder, meaning that affected individuals inherit two copies of the mutated ATP7B gene, one from each parent. Early diagnosis and treatment with chelating agents or zinc supplements can help prevent the progression of the disease and improve patient outcomes.

**Correct Answer:** D. Copper