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': "Ormond's disease is \nSelect and explain. \nA. Retractile testis, B. Idiopathic retro peritoneal lymphadenopathy, C. Idiopathic retro peritoneal fibrosis, D. Idiopathic mediastinotis", 'role': 'user'}, {'content': "Answer: C \nExplanation: In 70% cases of Ormond's disease\xa0Idiopathic\xa0retro peritoneal fibrosis is seen.", 'role': 'assistant'}]