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': 'A dense renogram is obtained by: \nSelect and explain. \nA. Dehydrating the patient, B. Increasing the dose of contrast media, C. Rapid (Bolus) injection of dye, D. Using non ionic media', 'role': 'user'}, {'content': 'Answer: C \nExplanation: In a normally functioning kidney, rapid injection of the dye gives an uniform dense nephrogram because of appearance of contrast material in the proximal tubule and peritubular capillaries within 30seconds of injection and approximately 2 minutes later contrast agent begin to appear in the calyces. Ref: Diseases of The Kidney and Urinary Tract By Robe W. Schrier, Page 338, 706', 'role': 'assistant'}]