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': 'Tetracycline should be avoided from: \nSelect and explain. \nA. 4 months to 8 years after birth, B. 4 months in utero to 8 years after birth, C. 4 weeks in utero to 8 years after birth, D. 12 weeks in utero to 8 years after birth', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Tetracycline when given from mid-pregnancy to 5 months of extrauterine life, the deciduous teeth are affected with discoloration. When given between 3 months to 6 years of age, they affect the crowns of permanent anterior dentition. They should be avoided from 4 months in utero to 8 years.', 'role': 'assistant'}]