This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Rectum and anal canal, Subject name: Surgery
[{'content': 'Most common location of solitary rectal ulcer is: \nSelect and explain. \nA. Anterior wall, B. Right lateral wall, C. Posterior wall, D. Left lateral wall', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Most common location of solitary rectal ulcer is: Anterior wall Solitary rectal ulcer syndrome (SRUS)- benign disease C/F- Rectal bleeding Copious mucus discharge Prolonged excessive straining, feeling of incomplete defecation, constipation Perineal and abdominal pain Histopathological features- obliteration of the lamina propria by fibrosis and smooth muscle fibers extending from a thickened muscularis mucosa to the lumen. COLONOSCOPY WITH BIOPSY is the investigation of choice', 'role': 'assistant'}]