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: Pathology
[{'content': 'The commonest site of endometriosis \nSelect and explain. \nA. Vagina, B. Ovary, C. Urinary bladder, D. Peritoneal cavity', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Endometriosis\n\nEndometriosis (ectopic endometrium) is the term used to describe the presence of endometrium (endometrial glands or stroma) in abnormal locations outside the uterus.\nIt occurs in following sites, in decreasing order of frequency -\n\n1. Ovary\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0 2. Uterine ligaments\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0 3. Rectovaginal septum\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0 4. Pelvic peritoneum\n5. Laprotomy scar\xa0 \xa0 \xa0 \xa06. Umbilicus, vagina, vulva or appendix.\n\nAdenomyosis is the presence of endometrial tissue in the uterine wall, i.e., in the myometrium.', 'role': 'assistant'}]