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': 'Collimating the X-ray beam reduces the formation of\nscattered radiation by \nSelect and explain. \nA. Selective removal of soft radiation, B. Selective removal of hard radiation, C. Reducing the size of X-ray beam, D. Reduction of beam intensity by 50%', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]