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
Fetal Hb is replaced by adult Hb completly at ? 
Select and explain. 
A. At bih, B. 2 months, C. 4 months, D. 6 months
D: 6 months
Answer: D: 6 months 
Explanation: 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.