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: Dental
[{'content': 'The average "Leeway space" available in each half of the\nmaxilla is approximately \nSelect and explain. \nA. 0.9 mm, B. 2.9 mm, C. 4.0 mm, D. 6.9 mm', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]