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': 'Main source of prolactin in amniotic fluid is : \nSelect and explain. \nA. Decidua, B. Synctiotrophoblast, C. Cytotrophoblast, D. Yolksac of fetus', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Decidua is the main source of prolactin present in amniotic fluid. Decidual prolactin is not confused with human placental lactogen(hpl) which is produced only by the synctiotrophoblast. Ref:Williams Obs - 24 e pg 88.', 'role': 'assistant'}]