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: Gynaecology & Obstetrics
[{'content': 'Inhibin is secreted by : \nSelect and explain. \nA. Graffian follicle, B. Corpus luteum, C. Endometrium, D. Placenta', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Graffian follicle', 'role': 'assistant'}]