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: Pathology
[{'content': 'Which one of the following variants of renal cell carcinoma has the worst prognosis - \nSelect and explain. \nA. Papillary, B. Tubuloalveolar, C. Chromophobe, D. Sarcomatoid', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]