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
[{'content': 'Anal carcinoma is most commonly of type? \nSelect and explain. \nA. Adenocarcinoma, B. Epidermoid, C. Mixed, D. None of the above', 'role': 'user'}, {'content': "Answer: B \nExplanation: Epidermoid carcinoma of the anus includes squamous cell carcinoma, cloacogenic carcinoma, transitional carcinoma and basaloid carcinoma. The clinical behaviour and natural history of these tumors is similar. Ref: Schwaz 9/e, Page 1053; Maingot's 10/e, Page 1505.", 'role': 'assistant'}]