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
A woman should take continuously how many days of hormonal OC pills to prevent ovulation? 
Select and explain. 
A. 3 days, B. 5 days, C. 7 days, D. 9 days
C: 7 days
Answer: C: 7 days 
Explanation: A woman must take hormonal OCs for seven days continuously in order to prevent ovulation reliably Reference: WHO guidelines