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: Surgery
[{'content': "Commonest site of metastasis of Wilm's tumour is ? \nSelect and explain. \nA. Bones, B. Lungs, C. Liver, D. Brain", 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Lungs", 'role': 'assistant'}]