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 Radioactivity is \nSelect and explain. \nA. Curie, B. Becquerel, C. Roentgen, D. Sievert', 'role': 'user'}, {'content': 'Answer: B \nExplanation: SI unit - Becquerel\nOld unit - Curie', 'role': 'assistant'}]