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': 'Investigation of choice to demonstrate vesico-ureteric reflex: \nSelect and explain. \nA. IVP, B. Ultrasound, C. Contrast MCU, D. Cystoscopy', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. Contrast MCU', 'role': 'assistant'}]