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
[{'content': 'In embryo, Hemopoiesis is first demonstrable in \nSelect and explain. \nA. Yolk sac, B. Liver, C. Spleen, D. Bone marrow', 'role': 'user'}, {'content': 'Answer: A \nExplanation: 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', 'role': 'assistant'}]