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': 'Portwine stain disappears after \nSelect and explain. \nA. 1 Year, B. 2 Years, C. 5 Years, D. None of the above', 'role': 'user'}, {'content': "Answer: D \nExplanation: Portwine stain is a vascular malformation that usually doesn't resolve and persists throughout life.\nIt is associated with Sturge - Weber syndrome.", 'role': 'assistant'}]