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: Gynaecology & Obstetrics
[{'content': 'All are true about centchroman except : \nSelect and explain. \nA. Anti oestrogenic, B. Not a teratogen, C. Long acting pill, D. Failure is 10 per 100 women years', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Failure is 10 per 100 women years', 'role': 'assistant'}]