**Core Concept**
Cicatricial pemphigoid is an autoimmune disease characterized by the formation of autoantibodies against components of the basement membrane zone. The **salt split skin technique** is a diagnostic tool used to determine the location of these autoantibodies.

**Why the Correct Answer is Right**
In Cicatricial pemphigoid, the autoantibodies are typically directed against the **BP180** (bullous pemphigoid antigen 2) or **BP230** (bullous pemphigoid antigen 1) proteins. However, the most common antigen targeted in Cicatricial pemphigoid is **BP180**, which is a transmembrane protein.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it is not specified.
**Option B:** Incorrect because it is not the primary antigen in Cicatricial pemphigoid.
**Option C:** Incorrect because it is not the main antigen targeted.
**Option D:** Incorrect because it is not the primary antigen in this condition.

**Clinical Pearl / High-Yield Fact**
Cicatricial pemphigoid is a rare disease that primarily affects the mucous membranes, leading to blistering and scarring.

**Correct Answer:** D. BP180