This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Surgery
[{'content': 'Solitary rectal ulcer is \nSelect and explain. \nA. Due to anterior wall prolapsed, B. Malignant, C. Always treated by surgery, D. Easy to traet', 'role': 'user'}, {'content': "Answer: A \nExplanation: This is becoming a more commonly diagnosed problem. Classically, it takes the form of an ulcer on the anterior wall of the rectum. In this form, it must be differentiated from a rectal carcinoma or inflammatory bowel disease, paicularly Crohn's disease.it may be due to a combination of internal intussusception or anterior rectal wall prolapse and an increase in intrarectal pressure. Ref: Bailey & Love&;s Sho Practice of Surgery,E25,Page-1227", 'role': 'assistant'}]