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': 'Radiation protection shields are made up of: \nSelect and explain. \nA. Copper, B. Silver, C. Lead, D. Tin', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. Lead', 'role': 'assistant'}]