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: Skin
[{'content': 'Nail pitting is caused by all except ? \nSelect and explain. \nA. Lichen planus, B. Hypehyroidism, C. Fungal infection, D. Pityriasis Rosacea', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., Pityriasis Rosacea", 'role': 'assistant'}]