This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Inflammatory Bowel Disease, Subject name: Pathology
[{'content': "Backwash ileitis is seen in: \nSelect and explain. \nA. Crohn's disease, B. Ulcerative colitis, C. Colonic carcinoma, D. Ileal polyp", 'role': 'user'}, {'content': 'Answer: B \nExplanation: BACKWASH ILEITIS: - Extends contiguously backward from cecum without skip regions. - It is seen in ulcerative colitis where eventhough small intestine is normal, mild mucosal inflammation of distal ileum is seen.', 'role': 'assistant'}]