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: Medicine
[{'content': "Backwash ileitis is seen in \nSelect and explain. \nA. Ulcerative colitis, B. Crohn's disease, C. Colonic carcinoma, D. heal polyp", 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Ulcerative colitis Ulcerative colitis always involves the rectum and extends proximally in continuous fashion to involve pa or all pa of the colon. Involvement of terminal ileum in ulcerative colitis is called backwash ileitis", 'role': 'assistant'}]