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: Social & Preventive Medicine
[{'content': 'M.C. retroperitoneal tumour is - \nSelect and explain. \nA. Fibrosarcoma, B. Liposarcoma, C. Dermoid cyst, D. Rhabdosarcoma', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans is \'b\' ie Liposarcoma The most common primary malignancy of the retroperitoneum is sarcoma.(Ref Sabiston) "In the retroperitoneal location, well-differentiated and dedifferentiated liposarcoma and leiomyosarcoma are the most common histiotypes, whereas in the visceral location, GISTs are found most commonly."- Devita\'s Oncology', 'role': 'assistant'}]