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': 'Vertical section of ramus of mandible is done in which condition: \nSelect and explain. \nA. Mandibular protrusion, B. Mandibular retrusion, C. Maxillary prognathism, D. Maxillary retrognathism', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]