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 one of the following is NOT an epithelial tumour of the ovary: September 2012 \nSelect and explain. \nA. Serous cystadenoma, B. Brenner tumour, C. Clear cell tumour, D. Endodermal sinus tumour', 'role': 'user'}, {'content': 'Answer: D \nExplanation: 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', 'role': 'assistant'}]