Okay, let's tackle this question. The patient is a 30-year-old male with silvery scales on the elbows and knees that bleed when removed. The key here is the presentation of silvery scales and bleeding upon removal, which is a classic sign. I need to think about the differential diagnoses for scaly skin lesions.

Psoriasis comes to mind immediately because it often presents with well-demarcated, erythematous plaques covered with silvery-white scales. The location on elbows and knees is typical. The Koebner phenomenon isn't mentioned here, but the bleeding upon scale removal is a key point. Another possibility could be tinea, but tinea usually has a more annular pattern and might have central clearing. However, the description here doesn't mention ring-shaped lesions, so that's less likely. Contact dermatitis might cause redness and scaling, but it's usually more itchy and not typically silvery. Lichen planus has a different presentation with purple, polygonal papules and a "strawberry" appearance under the skin.

Wait, the question mentions that the scales bleed when removed. That's a classic sign of psoriasis called the Auspitz sign. When you remove the scales, there's a pinpoint bleeding due to the disruption of the capillary loops in the epidermis. So the presence of Auspitz sign strongly points towards psoriasis. Other conditions like seborrheic dermatitis might have scaling, but not the silvery type and not the bleeding. Also, the location on elbows and knees is very common for psoriasis vulgaris.

So the correct answer should be psoriasis. Let me check the options again. The options aren't listed, but the correct answer is likely one of the options given. The key points here are the silvery scales, location, and Auspitz sign. The other options like tinea, eczema, or lichen planus don't fit as well. Therefore, the probable diagnosis is psoriasis vulgaris.

**Core Concept**
This question tests the recognition of **psoriasis vulgaris**, a chronic inflammatory skin condition characterized by **silvery-white scales** over **erythematous plaques**, commonly located on extensor surfaces like elbows and knees. The **Auspitz sign** (pinpoint bleeding after scale removal) is a hallmark diagnostic feature.

**Why the Correct Answer is Right**
The clinical presentation matches **psoriasis vulgaris**:
1. **Silvery scales** result from hyperproliferation of keratinocytes and parakeratosis.
2. **Bleeding on scale removal (Auspitz sign)** occurs due to disrupted capillary loops in the epidermis.
3. **Elbow/knee predilection** aligns with classic distribution for psoriasis.
Pathogenesis involves immune-mediated T-cell activation and cytokine release (e.g., TNF-α, IL-17), leading to epidermal hyperplasia.

**Why Each Wrong Option is Incorrect**
**Option A:** *Tinea corporis* presents with annular, scaly plaques with central clearing, not silvery scales or Auspitz sign.
**Option B:** *Atopic dermatitis* causes pruritic, erythematous, lichenified lesions in flexural areas, not silvery scaling.
**Option C

✓ Correct Answer: C. Psoriasis