**Core Concept**
Pityriasis rosea is a common skin condition characterized by the appearance of oval-shaped erythematous patches with fine central scales, typically distributed along the skin tension lines. This distinctive pattern is a result of the immune system's response to a viral infection, specifically human herpesvirus 6 (HHV-6).

**Why the Correct Answer is Right**
The characteristic distribution of pityriasis rosea along skin tension lines, also known as Langer's lines, is due to the orientation of the skin's collagen fibers. As the skin expands, the collagen fibers are stretched, leading to the appearance of the patches. The fine central scale is a result of the desquamation of the epidermal layer, which is a hallmark of this condition. The oval shape of the patches is also a distinguishing feature, as it reflects the shape of the affected skin appendages.

**Why Each Wrong Option is Incorrect**
**Option A:** Tinea versicolor is a fungal infection that typically presents with hypopigmented patches, not erythematous patches with fine central scales.
**Option C:** Lichen planus is an autoimmune condition that presents with polygonal, violaceous papules, not oval-shaped erythematous patches.
**Option D:** Seborrheic dermatitis is a condition that affects the scalp, face, and torso, but it typically presents with greasy, yellowish scales, not fine central scales.

**Clinical Pearl / High-Yield Fact**
Pityriasis rosea often follows a viral prodrome, such as upper respiratory tract infections or gastroenteritis, and may be triggered by stress, fatigue, or other systemic illnesses.

**Correct Answer:**
✓ Correct Answer: B. Pityriasis rosea