This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abdominal Radiography, Subject name: Radiology
[{'content': "Sign (Arrows) on Abdominal radiograph indicate \nSelect and explain. \nA. Crohn's disease, B. Ulcerative colitis, C. Small bowel obstruction, D. Ileocaecal Tuberculosis", 'role': 'user'}, {'content': 'Answer: C \nExplanation: Small bowel obstruction {Sign: String of bead sign)', 'role': 'assistant'}]