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': "Duke's stage C2 refers to carcinoma - \nSelect and explain. \nA. Bladder penetrating the extravesical fat, B. Bladder with metastasis to internal iliac lymph nodes, C. With histological features of 75% anaplastic cells, D. Rectum with metastasis to inferior mesentric lymph nodes", 'role': 'user'}, {'content': "Answer: D \nExplanation: Duke's staging is used for colorectal cancer.\nIn Dukes 'C' stage, there is involvement of regional lymphnodes.\nDuke's staging has been explained earlier.", 'role': 'assistant'}]