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': 'True about cystic hygroma \nSelect and explain. \nA. Present in anterior triangle of neck, B. Sclerosing agents are not useful, C. Pre-operative MRI is crucial, D. Surgery is always indicated', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]