This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Haematology, Subject name: Pathology
Common site of hematopoiesis in fetus is 
Select and explain. 
A. Liver, B. Spleen, C. Bone marrow, D. Gut
A: Liver
Answer: A: Liver 
Explanation: Development of the Hematopoietic System. Primitive hematopoiesis is followed by definitive hematopoiesis in mice and humans. Embryonic hematopoiesis begins in the yolk sac and changes to definitive hematopoiesis in the fetal liver. The bone marrow becomes the principal site of hematopoiesis late in gestation Ref Robbins 9/e pg 138