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': 'According to Boyd classification of intermittent Claudication; Rest pain is seen in \nSelect and explain. \nA. Grade 1, B. Grade 2, C. Grade 3, D. Grade 4', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]