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
Molar-incisor hypoplasia in primary teeth at the occlusal level is due to developmental defect occurring during? 
Select and explain. 
A. Birth to 12 months, B. 4th month intra-uterine to birth, C. 22 months to 26 months, D. 24 months to 48 months
B: 4th month intra-uterine to birth
Answer: B: 4th month intra-uterine to birth 
Explanation: None