This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Obstetrics And Gynaecology, Subject name: Radiology
[{'content': 'Which of the following is associated with the least radiation in pregnancy? \nSelect and explain. \nA. X-ray, B. MRI, C. CTscan, D. VQscan', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans: b (MRI) Ref: Practical Radiotherapy- physics ami equipment 2nd ed/p.68MRI uses magnetic properties of hydrogen atoms to generate images.Increasing order of radiation:-X-ray< VQ scan < CT scan.', 'role': 'assistant'}]