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
Commonest type of Anal canal Ca is - 
Select and explain. 
A. Sq. cell Ca, B. Adeno Ca, C. Adenoacanthoma, D. Papillary type
A: Sq. cell Ca
Answer: A: Sq. cell Ca 
Explanation: Mainly 3 types of malignant neoplasm are seen in anal canal

Squamous cell Ca (MC)
Basal cell Ca (IInd mc)
Melanoma

Remember

MC type of rectal & colon Ca → Adenocarcinoma*.