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': 'Derive the magnification from the following illustration: \nSelect and explain. \nA. a/b, B. X/Y, C. a/(a-b), D. Both 1 and 2', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Magnification\nAll conventional radiographic images are magnified. Radiographs are “shadow pictures” and the size of the shadow depends upon the relative relationship of X-ray source, object and image receptor.', 'role': 'assistant'}]