This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Papulosquamous disorders, Subject name: Dental
[{'content': "Characterstic nail finding in lichen planus - \nSelect and explain. \nA. Pitting, B. pterygium, C. Beau's Lines, D. Hyperpigmentation of nails", 'role': 'user'}, {'content': 'Answer: B \nExplanation: NAIL CHANGES IN LICHEN PLANUS: 1.Early change- bluish red discolouration of proximal nail fold. 2.thinning of nail plate, koilonychia, longtudinal ridging, splitting(onychoschizia) 3. pterygium formation-wing shaped growth of proximal nail fold across the nail plate due to severe nail matrix involvement. it is a characteristic nail change in lichen planus 4. pup tent sign: proximal onycholysis with elevation of nail plate and longitudinal splitting ue to involvement of nail bed. 5. anonychia 6. melanonychia IADVL textbook of dermatology, page 1075', 'role': 'assistant'}]