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
In Duke's classification of colorectal carcinoma stageA means 
Select and explain. 
A. Involvement upto muscularis propria, B. Involvement beyond muscularis propria, C. Positive lymph node involvement, D. Distant metastasis
A: Involvement upto muscularis propria
Answer: A: Involvement upto muscularis propria 
Explanation: (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