This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Surgery
[{'content': "In Duke's classification of colorectal carcinoma stageA means \nSelect and explain. \nA. Involvement upto muscularis propria, B. Involvement beyond muscularis propria, C. Positive lymph node involvement, D. Distant metastasis", 'role': 'user'}, {'content': "Answer: A \nExplanation: (A) Involvement up to muscularis propria # Duke's prognostic classification> A-growth in colon/rectum only> B-growth extending to extrarectal tissues but no metastasis to regional lymph nodes> C-secondary deposits in regional lymph nodes", 'role': 'assistant'}]