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
Erythropoiesis in first two months of gestation age takes place in 
Select and explain. 
A. Yolk sac, B. Placenta, C. Amniotic sac, D. Chorion
A: Yolk sac
Answer: A: Yolk sac 
Explanation: In the first 2 month of gestation. the yolk sac is the main site of blood formation (MESOBLASTIC PHASE) Ref: Medical Physiology Indu Khurana 2015 edition pAge No:104