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': 'Radiation exposure is least in \nSelect and explain. \nA. CT pelvis, B. IVP, C. Cystography, D. Micturating cysto - Urethrogram', 'role': 'user'}, {'content': 'Answer: D \nExplanation: MCU :\xa01 - 2 (msv) - 60 chest x - ray.\nCystography :\xa01- 8 (msievert) - 90cxr.\nIVP :\xa02 - 4 -\xa0120cxr.\nCT pelvis :\xa010 - 500cxr.', 'role': 'assistant'}]