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: Pathology
[{'content': 'The combination of rest pain, colour changes, oedema and hyperaesthesia \nSelect and explain. \nA. Gangrene, B. Pregangrene, C. Necrosis, D. Vasculitis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]