**Core Concept**
The question is testing the student's ability to diagnose a migratory, pruritic skin eruption, which is a classic symptom complex often associated with various dermatological and systemic conditions. This symptom complex is characterized by the movement of the rash from one area of the body to another, accompanied by intense itching.

**Why the Correct Answer is Right**
The correct diagnosis is likely to be cholinergic urticaria, a type of physical urticaria. Cholinergic urticaria is caused by the release of histamine from mast cells in response to increased body temperature, which can be triggered by factors such as exercise, hot showers, or spicy foods. The symptoms of cholinergic urticaria typically include a migratory, pruritic skin eruption, often in the form of small, itchy wheals.

**Why Each Wrong Option is Incorrect**
**Option A:** Atopic dermatitis is a chronic skin condition characterized by dry, itchy skin, but it is not typically migratory and is usually more widespread.
**Option B:** Contact dermatitis is a type of skin inflammation caused by exposure to allergens or irritants, but it is typically localized to the area of contact and does not exhibit a migratory pattern.
**Option C:** Erythema multiforme is a type of skin rash that can be caused by various factors, including infections and medications, but it typically presents with a more complex and widespread rash pattern.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that migratory, pruritic skin eruptions can have various underlying causes, including systemic conditions such as cholinergic urticaria, and that a thorough history and physical examination are crucial in diagnosing these cases.

**Correct Answer: D. Cholinergic urticaria.**