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': '1st evidence of calcification of Upper 2nd premolar is seen in \nSelect and explain. \nA. at birth, B. 16 wk IU, C. 1 year after birth, D. 2 -2 ½ years after birth', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]