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': 'Cranial vault volume at 7 years is: \nSelect and explain. \nA. 3-Jan, B. 4-Jan, C. 2-Jan, D. 4-Mar', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]