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: Pathology
[{'content': 'Dose of radiation which leads to mucositis is: \nSelect and explain. \nA. 1000 rads., B. 1500-2000 rads., C. 2500-3000 rads., D. 3500-4000rads.', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]