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': 'The haematopoetic injury occurs at a dose of: \nSelect and explain. \nA. 2-7 Gy, B. 7-15 Gy, C. 40-50 Gy, D. > 50 Gy', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Acute radiation syndrome:\n\n2–7 Gy – Haematopoietic injury\n7–15 Gy – Injury\n> 50 Gy – CVS / CNS', 'role': 'assistant'}]