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: ENT
[{'content': 'Frontal sinuses may not be developed normally maximum up to what years of age ? \nSelect and explain. \nA. 2, B. 4, C. 8, D. 12', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]