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 carcinoma of type \nSelect and explain. \nA. Adeno carcinoma, B. Epidermoid, C. Mixed, D. None of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Epidermoid carcinoma of the anus includes squamous cell ca, cloacogenic ca, transitional ca & basaloid ca. The clinical behavior and natural history of these tumors is similar.', 'role': 'assistant'}]