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
The tendency of colonic carcinoma to metastasize is best assessed by 
Select and explain. 
A. Size of tumor, B. Carcinoembryonic antigen (CEA) levels, C. Depth of penetration of bowel wall, D. Proportion of bowel circumference involved.
C: Depth of penetration of bowel wall
Answer: C: Depth of penetration of bowel wall 
Explanation: None