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': 'Commonest type of Anal canal Ca is - \nSelect and explain. \nA. Sq. cell Ca, B. Adeno Ca, C. Adenoacanthoma, D. Papillary type', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Mainly 3 types of malignant neoplasm are seen in anal canal\n\nSquamous cell Ca (MC)\nBasal cell Ca (IInd mc)\nMelanoma\n\nRemember\n\nMC type of rectal & colon Ca → Adenocarcinoma*.', 'role': 'assistant'}]