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: Pathology
[{'content': 'Which of the following is most common type of ovarian tumors? \nSelect and explain. \nA. Granulosal cell tumor, B. Serous epithelial tumor, C. Mature teratoma, D. Dysgerminoma', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Serous epithelial tumor are the most common type of ovarian tumors.', 'role': 'assistant'}]