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': 'SI unit of dose of radiation absorption – \nSelect and explain. \nA. Rad, B. REM, C. Gray, D. Curie', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The old unit of radiation absorption is rad and new (SI) unit is gray.', 'role': 'assistant'}]