This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Surgery
Investigation of choice of depth of penetration and nodal stage in rectal carcinoma is 
Select and explain. 
A. CT, B. MRI, C. Transrectal USG, D. Barium meal
C: Transrectal USG
Answer: C: Transrectal USG 
Explanation: A colonoscopy is required if possible in all patients to exclude a synchronous tumour, be it an adenoma or a carcinoma. If a proximal adenoma is found, it can be conveniently snared and removed the colonoscope. If a synchronous carcinoma is present, the operative strategy will need changing. If a full colonoscopy is not possible, a CT colonography or barium enema can be performed Ref: Bailey & Love&;s Sho Practice of Surgery,E25,Page-1232