**Core Concept:** Alopecia refers to the loss of hair from the skin, which can be categorized into cicatricial and non-cicatricial types. Cicatricial alopecia is caused by scarring of the hair follicles, while non-cicatricial alopecia is characterized by the absence of scarring.

**Why the Correct Answer is Right:** Non-cicatricial alopecia is primarily caused by various factors that lead to hair follicle damage without causing scarring. This type of alopecia results in hair loss due to follicle dysfunction but maintains the integrity of the hair follicle sheath. The correct answer, **D. Trichotillomania**, is a psychiatric disorder characterized by recurrent, impulsive hair pulling behavior, leading to non-cicatricial alopecia.

**Why Each Wrong Option is Incorrect:**

A. **Cicatricial pemphigoid (Option A)**: This autoimmune disorder primarily affects the skin, causing scarring and alopecia areata. It is not the correct answer for non-cicatricial alopecia.

B. **Polycystic Ovarian Syndrome (PCOS) (Option B)**: Although PCOS can lead to alopecia, it primarily affects the ovaries, not hair follicles, making it an incorrect answer for non-cicatricial alopecia.

C. **Kerion (Option C)**: Kerion is a severe hair and skin disease caused by fungal infection (mainly caused by Microsporum canis) primarily affecting the scalp. Although it can lead to non-cicatricial alopecia, it is not the most suitable answer among the options provided.

**Clinical Pearls:** Non-cicatricial alopecia can be caused by various factors, including genetic predisposition, infections (e.g., Trichotillomania, PCOS, and Kerion) and psychological factors (e.g., Trichotillomania). While these conditions may lead to hair loss, they do not directly cause non-cicatricial alopecia. Trichotillomania, specifically, is characterized by the irresistible urge to pull out one's own hair, leading to alopecia areata and is the correct answer for non-cicatricial alopecia.