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
SI unit of radiation absorbed dose is 
Select and explain. 
A. Rem, B. Gray, C. Rad, D. C/kg
B: Gray
Answer: B: Gray 
Explanation: Absorbed dose - Gray (SI)
Exposure dose - C/kg (SI)
Dose equivalent - Sievert