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
The gold standard for the diagnosis of osteoporosis is – 
Select and explain. 
A. Dual energy X-ray absorptiometry, B. Single energy X-ray absorptiometry, C. Ultrasound, D. Quantitative computed tomography
A: Dual energy X-ray absorptiometry
Answer: A: Dual energy X-ray absorptiometry 
Explanation: Dual Energy X-ray absorptiometry (DEXA) is the gold standard and investigation of choice for diagnosis of osteoporosis.