This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Contraception, Subject name: Gynaecology & Obstetrics
[{'content': 'A woman should take continuously how many days of hormonal OC pills to prevent ovulation? \nSelect and explain. \nA. 3 days, B. 5 days, C. 7 days, D. 9 days', 'role': 'user'}, {'content': 'Answer: C \nExplanation: A woman must take hormonal OCs for seven days continuously in order to prevent ovulation reliably Reference: WHO guidelines', 'role': 'assistant'}]