This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Radiology
[{'content': 'Xray aifact is \nSelect and explain. \nA. A radiolucent area, B. Any abnormal opacity in the radiograph, C. Produced when patient moves while taking the film, D. All of the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Aifacts can present in a variety of ways including abnormal shadow noted on a radiograph or degraded image quality and have been produced by aificial means from hardware failure, operator error, and software (post-processing) aifacts. Common CausesImproper handling of the filmsErrors while processing the filmsPatient movement while taking the shootingCommon aifactsmotion aifact - due patient movement resulting in the distoed imageimage compositing (or twin/double exposure) - superimposition of two structures from different locations due to double exposure of same film/plateradio-opaque objects on or external to the patient (e.g. necklaces, piercings, buttons, hair)(Ref: Radiographic Imaging and Exposure, 4e. Mosby chapter 9)', 'role': 'assistant'}]