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': '"Target material" which produces X-rays in a diagnostic X-rays tube is made of: \nSelect and explain. \nA. Lead, B. Tungsten, C. Cobalt, D. Copper', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. Tungsten', 'role': 'assistant'}]