This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anal Malignancy, Subject name: Surgery
Margin of clearence for anal carcinoma is- 
Select and explain. 
A. 2 cm, B. 3 cm, C. 4 cm, D. 5 cm
A: 2 cm
Answer: A: 2 cm 
Explanation: Ans. is 'a' i.e., 2 cm o Wide local excision leaving a margin of at least 2.5 cm of tissue all round with block dissection of the inguinal nodes; If they' are involved.