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': 'At t = 0 there are 6 x 1023 radioactive atoms of a substance, which decay with a disintegration constant (A,) equal to 0.01/sec. What would be the initial decay rate? \nSelect and explain. \nA. 6 x 1023, B. 6 x 1022, C. 6 x 1021, D. 6 x 1021', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. 6 x 1021', 'role': 'assistant'}]