**Core Concept**
A melanocytic naevus surrounded by a depigmented halo is a clinical manifestation of an autoimmune response to melanocytes, leading to an inflammatory reaction. This phenomenon is characterized by the destruction of melanocytes in the halo surrounding the naevus, resulting in depigmentation.

**Why the Correct Answer is Right**
The correct answer is a type of autoimmune vitiligo, specifically a variant known as halo naevus or Sutton's naevus. The depigmentation surrounding the naevus is due to the immune system's attack on melanocytes, leading to their destruction. This is a form of autoimmune response, where the body's immune system mistakenly targets its own cells, in this case, the melanocytes.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not a recognized term in dermatology, and it does not accurately describe a melanocytic naevus surrounded by a depigmented halo.
* **Option B:** This option is not a specific condition related to melanocytic naevi and depigmentation.
* **Option C:** This option is not a recognized term in dermatology, and it does not accurately describe a melanocytic naevus surrounded by a depigmented halo.

**Clinical Pearl / High-Yield Fact**
Halo naevi are an important clinical sign, as they can be a precursor to the development of vitiligo, a chronic autoimmune skin condition characterized by the destruction of melanocytes, leading to white patches on the skin.

**Correct Answer:** C. Halo naevus