This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Skeletal system, Subject name: Radiology
Bone Density is best studied by - 
Select and explain. 
A. CT scan, B. DEXA scan, C. MRI scan, D. Bone scan
B: DEXA scan
Answer: B: DEXA scan 
Explanation: According to the guidelines for diagnosis and treatment, dual X-ray absorptiometry (DXA) still represents the "gold standard" for diagnosis of osteoporosis and fracture risk prediction.