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: Pathology
[{'content': 'The sensitive period for tetracycline induced discolouration in the permanent maxillary mandibular incisors and canines is \nSelect and explain. \nA. 3 months postpartum to 7th year of Life, B. 4 months in utero to 3 months postpartum, C. 5 months in utero to 9 months postpartum, D. Birth to 7th year', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]