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
All of the following protect against endometriosis except: 
Select and explain. 
A. Pregnancy, B. Nulliparity, C. Exercise, D. Smoking
B: Nulliparity
Answer: B: Nulliparity 
Explanation: 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.