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: Surgery
[{'content': 'Which of the following is the most common retro peritoneal sarcoma ? \nSelect and explain. \nA. Liposarcoma, B. Leomyo sarcoma, C. Fibrosarcoma, D. Neural sheath sarcoma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Retroperitoneal sarcomas account for 0.1%-0.2% of all malignant tumours and about 15% of all sarcomas. Liposarcoma is the most common type of retroperitoneal sarcoma (41%), followed by leiomyosarcoma, malignant fibrous histiocytoma, fibrosarcoma and other undifferentiated sarcomas', 'role': 'assistant'}]