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: Surgery
[{'content': 'Cystic hygroma - \nSelect and explain. \nA. Should be left alone, B. Excision of cyst at an early age, C. Spontaneous regression, D. Manifests in 2nd - 3rd decade', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Spontaneous regression may occur rarely in cystic hygroma.', 'role': 'assistant'}]