**Core Concept**
Dermographism is a type of physical urticaria characterized by the development of wheals (hives) in response to mechanical stimuli, such as scratching or rubbing of the skin. This condition is mediated by the release of histamine and other chemical mediators from mast cells.

**Why the Correct Answer is Right**
Dermographism occurs when the skin is subjected to mechanical stress, leading to the activation of mast cells and the release of histamine. This results in increased vascular permeability, smooth muscle contraction, and the characteristic wheal formation. The pathophysiology of dermographism is closely related to the release of histamine from mast cells, which is triggered by the mechanical stimulation of the skin.

**Why Each Wrong Option is Incorrect**
**Option B:** Urticaria pigmentosa is a type of cutaneous mastocytosis, characterized by the accumulation of mast cells in the skin, leading to the development of brownish-black macules or patches. While it can present with urticaria, it is not a type of physical urticaria.

**Option C:** Urticarial vasculitis is a type of vasculitis that presents with urticaria, but it is not a type of physical urticaria. It is characterized by inflammation of the blood vessels and can be associated with various underlying conditions.

**Option D:** Autoimmune urticaria is a type of chronic urticaria that is thought to be mediated by autoimmune mechanisms. While it is a type of urticaria, it is not a type of physical urticaria.

**Clinical Pearl / High-Yield Fact**
Dermographism can be triggered by various mechanical stimuli, including scratching, rubbing, or even tight clothing. Recognizing the role of mechanical stress in the development of dermographism is essential for accurate diagnosis and management.

**Correct Answer:**
✓ Correct Answer: A. Dermographism