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: Pharmacology
[{'content': 'One of the health benefits of the use of combined oral contraceptives in pre–menopausal women is that these contraceptives reduce the risk of: \nSelect and explain. \nA. Deep vein thrombosis, B. Migraine, C. Ovarian cancer, D. Ischemic stroke', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]