**Core Concept**
Vitiligo is a chronic autoimmune skin disorder characterized by the loss of melanocytes, leading to white patches on the skin. It is a complex disease involving both genetic and environmental factors.

**Why the Correct Answer is Right**
The most common type of vitiligo is **segmental vitiligo**, accounting for approximately 20-30% of cases. This type typically presents with symmetrical, well-demarcated patches on one side of the body, often on the face, neck, or arms. Segmental vitiligo is thought to result from an autoimmune response targeting melanocytes in specific dermatomes, leading to their destruction and subsequent loss of pigmentation.

**Why Each Wrong Option is Incorrect**
**Option A:** Non-segmental vitiligo is a more common type, but it usually presents with bilateral, symmetrical patches that can occur anywhere on the body, not just on one side.
**Option B:** Acrofacial vitiligo is another variant, but it typically affects the face and distal extremities, which is not the most common presentation.
**Option C:** Universal vitiligo is a rare and severe form where melanocytes are destroyed throughout the body, resulting in complete loss of pigmentation.

**Clinical Pearl / High-Yield Fact**
Remember the **"ABCD" mnemonic** for the four types of vitiligo: Acrofacial, Bilateral (non-segmental), Central, and Diffuse (universal).

**Correct Answer: C. Segmental vitiligo**