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: Gynaecology & Obstetrics
[{'content': 'Which of the following germ cell tumor of ovary has significant rate of bilateral ovarian involvement \nSelect and explain. \nA. Teratoma, B. Dysgerminoma, C. Endodermal sinus tumor, D. Choriocarcinoma', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Dysgerminomas are only germ cell tumors with a significant rate of bilateral ovarian involvement (15 to 20 percent).', 'role': 'assistant'}]