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: Radiology
[{'content': 'Which of the following has greater bone density? \nSelect and explain. \nA. Posterior mandible, B. Posterior maxilla, C. Anterior maxilla, D. Anterior mandible', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]