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: Medicine
[{'content': 'Purple toe syndrome is associated with which of the following drugs? \nSelect and explain. \nA. Warfarin, B. Phenytoin, C. Theophylline, D. Thalidomide', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]