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: Unknown
[{'content': 'Which drugs needs continuous monitoring of prothrombin time? \nSelect and explain. \nA. Aspirin, B. Lepirudin, C. Digoxin, D. Warfarin', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ref. KDT. Page. 624', 'role': 'assistant'}]