This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General obstetrics, Subject name: Gynaecology & Obstetrics
In embryo, Hemopoiesis is first demonstrable in 
Select and explain. 
A. Yolk sac, B. Liver, C. Spleen, D. Bone marrow
A: Yolk sac
Answer: A: Yolk sac 
Explanation: In the early embryo, hemopoiesis is demonstrable first in the yolk sac, followed by the liver and finally bone marrow.Reference: William&;s Obstetrics; 24th edition; Chapter 7; Embryogenesis and Fetal Morphological Development