**Question:** Skin condition which resolves on its own is -

A. Impetigo
B. Eczema
C. Urticaria
D. Acne vulgaris

**Core Concept:**
The question is asking about a skin condition that usually improves without specific treatment within a reasonable time frame, indicating a self-limiting process. In medical terminology, these conditions often involve an immune response, inflammation, or infection.

**Why the Correct Answer is Right:**
Dermatological conditions that are self-limiting usually represent a localized immune response or an infection that is resolved due to the patient's immune system. In the case of acne vulgaris (D), the influx of inflammatory cells and subsequent healing leads to improvement over time.

**Why Each Wrong Option is Incorrect:**

A. Impetigo (Impetigo) is a skin infection caused by bacteria (usually Streptococcus pyogenes or Staphylococcus aureus) and typically requires antibiotic treatment for resolution.

B. Eczema (atopic dermatitis) is a chronic inflammatory skin condition that may worsen or improve over time but does not inherently resolve on its own.

C. Urticaria (hives) is a skin condition characterized by itchy, red, elevated, and possibly pruritic (itchy) skin lesions. In most cases, urticaria resolves within days or weeks without specific treatment.

**Clinical Pearl:**
Understanding the natural history of skin conditions helps in managing patient expectations and choosing appropriate interventions when necessary. In the case of acne vulgaris, patients may benefit from topical retinoids, antibiotics, or oral tetracyclines to hasten the healing process, but they should be aware that most cases will resolve on their own within a few months to a year.

**Correct Answer:** Acne vulgaris (D)