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': 'Withdrawal bleeding with progesterone seen in otherwise amenorrhoeic woman due to : \nSelect and explain. \nA. Hypogonadotrophic hypogonadism, B. Anovulation, C. Ovarian failure, D. TB endometritis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. is b i.e. Anovulation', 'role': 'assistant'}]