This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endometriosis, Subject name: Gynaecology & Obstetrics
[{'content': 'All of the following protect against endometriosis except: \nSelect and explain. \nA. Pregnancy, B. Nulliparity, C. Exercise, D. Smoking', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. is b, i.e. NulliparityEndometriosis is a hyper estrogenic condition and is thus more common in Nulliparous females.Protective factors are multiparity, pregnancy, smoking and exercise.', 'role': 'assistant'}]