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': 'Oral contraceptive pills give protection against which of the following cancer ? \nSelect and explain. \nA. Hepatic, B. Ovary, C. Cervix, D. Breast', 'role': 'user'}, {'content': "Answer: B \nExplanation: The incidence of ovarian cancer is reduced by 40% and uterine malignancy by 50% if taken for 1 year, and this effect lasts as long as 10 years after stoppage. The risk decreases with duration of its use. Reference : Shaw's Texbook of Gynaecology 16th edition page no 274", 'role': 'assistant'}]