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': 'Radioactive gold is used in: \nSelect and explain. \nA. Bladder tumours, B. Malignant ascites, C. Gliomas, D. None', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. Malignant ascites', 'role': 'assistant'}]