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: Medicine
[{'content': 'This clinical sign is seen in <img src=" /> \nSelect and explain. \nA. Carcinoma colon, B. Ulcerative colitis, C. Crohn\'s disease, D. Tuberculosis', 'role': 'user'}, {'content': 'Answer: C \nExplanation: This is a contrast study showing string sign of KantorIn Crohn&;s disease, edema, bowel wall thickening, and fibrosis of the bowel wall within the mass account for the radiographic "string sign" of a narrowed intestinal lumen.Ref: Harrison 19e pg: 1953', 'role': 'assistant'}]