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
[{'content': 'Bone Density is best studied by - \nSelect and explain. \nA. CT scan, B. DEXA scan, C. MRI scan, D. Bone scan', 'role': 'user'}, {'content': 'Answer: B \nExplanation: 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.', 'role': 'assistant'}]