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: Anatomy
[{'content': 'HcG is secreted by : \nSelect and explain. \nA. Trophoblast cells, B. Amniotic membrane, C. Fetal yolk sac, D. Hypothalamus', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Synctiotrophoblasts are the principal site of protein and steroid hormones in pregnancy HcG is synthesized by synctiotrophoblast . Ref :Dutta Obs 9 e pg 53.', 'role': 'assistant'}]