This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
[{'content': 'A 30 years old male presented with silvery scales on elbow and knee, that bleed on removal. The probable diagnosis is – \nSelect and explain. \nA. Pityriasis, B. Seborrhoeic dermatitis, C. Psoriasis, D. Secondary syphilis', 'role': 'user'}, {'content': "Answer: C \nExplanation: Morphology of papules/plaques in various papulosquamotas disorders\n\nPsoriasis -\xa0Erythematous papules and plaques on extensors (elbow & knee\nLichen planus -\xa0Violaceous papules with Wickham's striae an flexural surface\nPityriasis rosea -\xa0Annular plaques on Trunk\nSeborrheic dermatitis - Yellowish, follicular papules on scalp and face\xa0\nPityriasis rubra pilaris -\xa0Erythematous follicular papules on Trunk & dorsum of hand\nSecondary syphilis -\xa0Dusky erythematous papules\nPityriasis lichenoides\xa0et varioliformis acuta -\xa0Erythematous edematous papules\xa0surmounted by vesicles/crust\n\nComing to question\nClues in this question are :-\n\nCharacterstic scales → silver scale\nInvolvement of elbow & knee\nBleeding on scale removal → Auspitz sign", 'role': 'assistant'}]