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: Pediatrics
[{'content': 'Fetal Hb is replaced by adult Hb completly at ? \nSelect and explain. \nA. At bih, B. 2 months, C. 4 months, D. 6 months', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., 6 months Synthesis of HbF decreases rapidly postnatally, and by 6-12 months of age only a trace is present.", 'role': 'assistant'}]