**Core Concept**
Scurvy is a disease caused by a lack of **vitamin C** (ascorbic acid) in the diet. Vitamin C is essential for the production of **collagen**, a protein that gives structure to skin, bones, and connective tissue.

**Why the Correct Answer is Right**
Vitamin C deficiency leads to impaired collagen synthesis, resulting in symptoms such as fatigue, malaise, and connective tissue defects. The **enzyme prolyl hydroxylase** requires vitamin C as a cofactor to hydroxylate proline residues in collagen, which is crucial for its stability and function.

**Why Each Wrong Option is Incorrect**
**Option A:** Not provided, assuming it's an incorrect option.
**Option B:** Not provided, assuming it's an incorrect option.
**Option C:** Not provided, assuming it's an incorrect option.
**Option D:** Not provided, assuming it's an incorrect option.

**Clinical Pearl / High-Yield Fact**
A classic symptom of scurvy is **perifollicular petechiae**, which are small hemorrhages around hair follicles. Scurvy can be prevented and treated with a diet rich in vitamin C, found in foods such as citrus fruits and leafy green vegetables.

**Correct Answer:** D. Vitamin C