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 Primary Upper 1st molar is seen in \nSelect and explain. \nA. 14 wk IU, B. 16 wk IU, C. 17 wk IU, D. 15 wk IU', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]