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': 'All of the following mechanisms might account for a reduce-risk of upper genital tract infection in users of progestin - releasing lUDs, except: \nSelect and explain. \nA. Reduced retrograde menstruation, B. Decreased ovulation, C. Thickened cervical mucus, D. Decidual changes in the endometrium', 'role': 'user'}, {'content': "Answer: B \nExplanation: Decreased ovulation does not protect from upper genital tract infection. Also it doesn't inhibit ovulation in all women. THE TEXTBOOK OF GYNAECOLOGY SHEILA BALAKRISHNAN SECOND EDITION PAGE NO 379", 'role': 'assistant'}]