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': 'In reduction genioplasty \nSelect and explain. \nA. Symphysis part of mandible is reduced, B. Symphysis part of mandible is advanced, C. Parasymphysis part of the mandible is reduced, D. Parasymphysis part of the mandible is advanced', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]