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': 'CT scan was invented by: \nSelect and explain. \nA. Geoffrey Hounsfield, B. Eric Storz, C. lohn Snow, D. Takashita Koba', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Geoffrey Hounsfield', 'role': 'assistant'}]