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': "How many Champy's osteosynthesis lines exist behind and in the front end of mental foramen: \nSelect and explain. \nA. 2 ahead of and 1 behind the mental foramen., B. 1 ahead of and 2 behind the mental foramen., C. 2 ahead of and 2 behind the mental foramen., D. 1 ahead of and 1 behind the mental foramen.", 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]