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: Surgery
[{'content': 'All are causes of dynamic intestinal obstruction except \nSelect and explain. \nA. Gall stones, B. Intussusception, C. Mesentric vascular occlusion, D. Bands', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]