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': 'Critical Limb ischemia results from \nSelect and explain. \nA. Mild Arterial Occlusive Disease, B. Moderate Arterial Occlusive disease, C. Severe Arterial occlusive disease, D. All of the above', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]