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': 'Ovarian tumours are commonly arise from : \nSelect and explain. \nA. Stroma, B. Surface epithelium, C. Germinal epithelium, D. Endoderm', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Surface epithelium', 'role': 'assistant'}]