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
[{'content': 'Most sensitive and specific investigation for screening of Renovascular hypertension – \nSelect and explain. \nA. MRI, B. Captopril enhanced radionuclide scan, C. Spiral CT Scan, D. Duplex – Doppler flow study', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]