This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Blood: RBCs, Anemia, and Polycythemia, Subject name: Physiology
Not a site of hematpoiesis in fetus - 
Select and explain. 
A. Kidney, B. Liver, C. Spleen, D. Yolk sac
A: Kidney
Answer: A: Kidney 
Explanation: Ans. is 'a' i.e., Kidney Erythropoies siteso Intrauteriney 0-10 weeksy 10 weeks - 5 monthsy 5 month onward-Yolk sac-Liver (maj or organ) and spleen- Bone marrowo After birthUpto 20 years - Bone marrow of all bonesAfter 20 years - Flat bones of axial skeletal and proximal end of humerus and femur.