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
Radiation injury to the haemopoietic system of the bone marrow occurs when the whole body exposure ranges between: 
Select and explain. 
A. 50-100 rads, B. 200-1000 rads, C. 1000-5000 rads, D. 10,000 rads to more
B: 200-1000 rads
Answer: B: 200-1000 rads 
Explanation: None