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': 'Organ which is commonly involved in Retroperitoneal fibrosis is \nSelect and explain. \nA. Large intestine, B. Pancreas, C. Ureter, D. Kidney', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ureter is involved in Retro peritoneal fibrosis leading to Hydro Ureteno Nephrosis.', 'role': 'assistant'}]