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: Surgery
[{'content': 'How is prolactin stimulated so it can also stimulate the production of breast milk in return? \nSelect and explain. \nA. Acinar cells start producing colostrum., B. Progesterone levels are reduced by the delivery of the placenta., C. The letdown reflex takes place., D. Progesterone levels increase after the delivery of the placenta.', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B:\xa0As progesterone decreases, prolactin is stimulated.\nA:\xa0Acinar cells are only responsible for the production of colostrum.\nC:\xa0The letdown reflex is activated whenever the mother hears a baby crying or thinks about her baby.\nD:\xa0The progesterone should decrease to stimulate the release of prolactin.', 'role': 'assistant'}]