**Core Concept**
Mad Cow disease, also known as Bovine Spongiform Encephalopathy (BSE), is a neurodegenerative disorder caused by a misfolded protein called a prion. In humans, this prion can cause a similar condition known as variant Creutzfeldt-Jakob disease (vCJD).

**Why the Correct Answer is Right**
The misfolded prion protein in BSE can be transmitted to humans through the consumption of contaminated beef products, leading to vCJD. This condition is characterized by a rapid progression of neurological symptoms, including dementia, ataxia, and myoclonus. The prion protein is resistant to heat, radiation, and most disinfectants, making it difficult to eradicate. The prion protein is also not affected by the body's normal mechanisms for protein degradation, allowing it to accumulate and cause cellular damage.

**Why Each Wrong Option is Incorrect**
**Option A:** Alzheimer's disease is a different neurodegenerative disorder caused by the accumulation of beta-amyloid plaques and tau protein tangles, not prions.
**Option B:** Huntington's disease is an autosomal dominant disorder caused by an expansion of CAG repeats in the Huntingtin gene, leading to a toxic protein product that causes neuronal degeneration.
**Option C:** Parkinson's disease is a neurodegenerative disorder characterized by the accumulation of alpha-synuclein protein and the loss of dopamine-producing neurons in the substantia nigra.

**Clinical Pearl / High-Yield Fact**
The risk of vCJD can be minimized by avoiding the consumption of beef products from countries with a high incidence of BSE, such as the UK.

**Correct Answer: D. Variant Creutzfeldt-Jakob disease (vCJD)**