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': 'Tungsten coil contains the following element: \nSelect and explain. \nA. Thorium., B. Indium., C. Galium., D. None.', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]