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 one of the following is NOT an epithelial tumour of the ovary: September 2012 
Select and explain. 
A. Serous cystadenoma, B. Brenner tumour, C. Clear cell tumour, D. Endodermal sinus tumour
D: Endodermal sinus tumour
Answer: D: Endodermal sinus tumour 
Explanation: Ans. D i.e. Endodermal sinus tumour Endodermal sinus (yolk sac) tumour is a rare tumour but the second most common of germ cell origin