This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Female Genital Tract, Subject name: Pathology
[{'content': 'Most common ovarian tumor \nSelect and explain. \nA. Serous cystadenoma, B. Choriocarcinoma, C. Teratoma, D. Fibroma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (a) Serous cystadenoma(Ref: Robbins 9th/pg 1023)*Most ovarian tumors are surface epithelial (65-70%)*Serous cystadenoma is the most common surface epithelial tumor', 'role': 'assistant'}]