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
First evidence of calcification of maxillary permanent central incisors occurs at: 
Select and explain. 
A. 3-4 months, B. 10-12 months, C. 2-3 years, D. 3-4 years
A: 3-4 months
Answer: A: 3-4 months 
Explanation: None