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': 'The most common complication of an ovarian tumor is : \nSelect and explain. \nA. Torsion, B. Hemorrhage, C. Infection, D. Hyaline change', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Torsion', 'role': 'assistant'}]