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: Dental
[{'content': 'The SI unit of absorbed dose of radiation is:` \nSelect and explain. \nA. Gray, B. Rad, C. Sv, D. Kerma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]