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
Which of the following germ cell tumor of ovary has significant rate of bilateral ovarian involvement 
Select and explain. 
A. Teratoma, B. Dysgerminoma, C. Endodermal sinus tumor, D. Choriocarcinoma
B: Dysgerminoma
Answer: B: Dysgerminoma 
Explanation: Dysgerminomas are only germ cell tumors with a significant rate of bilateral ovarian involvement (15 to 20 percent).