This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
[{'content': 'Beta HCG is secreted by ? \nSelect and explain. \nA. Ovary, B. Pituitary, C. Corpus luteum, D. Placenta', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., Placenta", 'role': 'assistant'}]