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': 'Conformation radiotherapy uses: \nSelect and explain. \nA. Multileaf collimator, B. Single leaf collimator, C. Cone, D. Cylinder', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Multileaf collimator', 'role': 'assistant'}]