This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Small & Large Intestine, Subject name: Surgery
[{'content': 'Commonest site of carcinoma colon is: \nSelect and explain. \nA. Right side colon, B. Left side colon, C. Transverse colon, D. Caecum', 'role': 'user'}, {'content': 'Answer: B \nExplanation: (Left side colon): Ref: 1177-LB (1181-B &L 25th)Adenocarcinoma of the colon: - Tumours are more common in the left colon and rectum* Microscopically the neoplasm is a columnar cell carcinoma* Macroscopically the tumour may take one of four forms (Annular, Tubular ulcer, cauliflower/ Type 4 cauliflower is the least malignant form* All carcinoma starts as benign adenoma, the so called "adenoma-carcinoma sequence"* Annular variety gives rise to obstructive symptoms and where as the others more commonly will present with bleeding.Symptoms and signs of colorectal cancer(A) Right sided tumours: Iron deficiency anemia, abdominal pain(B) Left sided tumours: Rectal bleeding, alteration in bowel habit, tenesmus obstruction(C) Metastatic disease: Jaundice, ascitis, hepatomegaly, other symptoms and signs from rare sites of metastasis.', 'role': 'assistant'}]