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: Physiology
[{'content': 'Prothrombin time is useful for \nSelect and explain. \nA. Detection of clot retraction, B. Platelet count, C. In hemophilia, D. For evaluation in a patient taking anticoagulant drugs', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]