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: Medicine
[{'content': 'All are complications of ulcerative colitis, except: \nSelect and explain. \nA. Haemorrhage, B. Stricture, C. Malignant change, D. Fistula formation', 'role': 'user'}, {'content': "Answer: D \nExplanation: Fistula formation is a hallmark feature of Crohn's , since the transmural inflammation is the norm in Crohn's disease. In ulcerative colitis it is always a paial thickness involvement and hence the fistula is not formed.", 'role': 'assistant'}]