This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Inflammatory Bowel Diseases, Subject name: Medicine
[{'content': "Backwash ileitis is seen in - \nSelect and explain. \nA. Ulcerative colitis, B. Crohn's disease, C. Colonic carcinoma, D. Ileal polyp", 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e.. Ulcerative colitiso Ulcerative colitis always involves the rectum and extends proximally in continuous fashion to involve part or all part of the colon.# Involvement of terminal ileum in ulcerative colitis is called backwash ileitis.", 'role': 'assistant'}]