This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General, Subject name: Skin
[{'content': 'Pterygium of nail is seen in? \nSelect and explain. \nA. Psoriasis, B. Pemphigus, C. Pemphigoid, D. Lichen planus', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. (d) Lichen planusRef: Roxburg 17th ed p 144, Rooks Thed p 42.1-42.14', 'role': 'assistant'}]