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: Radiology
[{'content': 'The unit of measurement of absorbed dose in X-ray is \nSelect and explain. \nA. Curie, B. Sievert, C. Gray, D. Kerma', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]