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': 'A major indication for orthognathic surgery before puberty is \nSelect and explain. \nA. Transverse deficiency of maxilla, B. Ankylosis of mandible, C. Prognathic mandible, D. Hyperdivergent facial pattern with anterior open bite', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]