This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
[{'content': 'Erythropoiesis in gestation age takes place in \nSelect and explain. \nA. Yolk sac, B. Placenta, C. Amniotic sac, D. Chorion', 'role': 'user'}, {'content': 'Answer: A \nExplanation: In the first 2 months of gestation yolk, sac is the main site of Erythropoiesis(mesoblastic stage) Ref: Medical Physiology Indu Khurana 2015 page No:104 In early weeks of embryonic life, primitive nucleated red cells are producedin yolk sac. During middle trimester of gestation-liver (also spleen,lymph nodes in reasonable numbers) During last month of gestation and after bih- exclusively in the bone marrow', 'role': 'assistant'}]