**Core Concept**
Psoriasis is a chronic autoimmune skin condition characterized by hyperproliferation of keratinocytes, leading to thickened, scaly skin lesions. Nail changes are a common extracutaneous manifestation of psoriasis, affecting up to 50% of patients.

**Why the Correct Answer is Right**
Psoriasis-related nail changes include pitting, onycholysis (separation of the nail from the nail bed), subungual hyperkeratosis (thickening of the nail plate), and nail bed erythema. These changes result from the abnormal immune response in psoriasis, which affects the nail matrix and nail bed. The nail matrix is the area beneath the cuticle where new nail cells are produced, and it is sensitive to the inflammatory mediators released in psoriasis.

**Why Each Wrong Option is Incorrect**
**Option A:** is incorrect because pitting is a characteristic nail change in psoriasis, resulting from the abnormal keratinocyte proliferation and immune response in the nail matrix.
**Option B:** is incorrect because onycholysis is a common nail change in psoriasis, caused by the separation of the nail plate from the nail bed due to the inflammatory mediators released in the condition.
**Option C:** is incorrect because subungual hyperkeratosis is a nail change associated with psoriasis, characterized by thickening of the nail plate.

**Clinical Pearl / High-Yield Fact**
Classic nail changes in psoriasis include pitting, onycholysis, subungual hyperkeratosis, and nail bed erythema. These changes are often associated with other extracutaneous manifestations of psoriasis, such as joint inflammation and eye problems.

**Correct Answer: D.**