This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology and breast, Subject name: Surgery
[{'content': 'Struma ovarii is a \nSelect and explain. \nA. Metastatic tumor, B. Teratoma, C. Sex cord tumor, D. Surface epithelial tumor', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Struma is a river in europe,along its banks endemic goitre was noted. Strauma is loosely used for goitre in europe. A Struma ovarii benign ovarian tumor is a form of teratoma that contains mostly thyroid tissue, which may develop thyrotoxicosis. Source : Bailey and love 26th edition Pg : 748', 'role': 'assistant'}]