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': 'True about struma ovarii -a) Ectopic thyroid tissueb) Ectopic ovarian tissuec) It is benignd) It is included in teratoma \nSelect and explain. \nA. abc, B. ad, C. bc, D. acd', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Struma ovarii is the presence of mature thyroid tissue as a major cellular component in an ovarian tumor.\nOvarian tumor is nearly always a teratoma.\nMost of the tumors are benign and in some cases thyrotoxicosis develops.', 'role': 'assistant'}]