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': "Abdominal ultra-sonography in a 3 year old boy show a solid circumscribed hypoechnoic renal mass. Most likely diagnosis is - \nSelect and explain. \nA. Wilm's tumor, B. Renal cell carcinoma, C. Mesoblastic nephroma, D. Oncocytoma", 'role': 'user'}, {'content': "Answer: A \nExplanation: Amongst the given options only Wilms tumor is common at 3 years of age :-\n\t\xa0Wilm's tumor\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0 → young children (mean 3 years)\n\tMesoblastic nephroma \xa0 \xa0 → < 1 year\n\tRenal cell carcinoma \xa0 \xa0 \xa0 \xa0→\xa0> 40 years\n\tOncocytoma \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0→\xa025-95 years (mean 65)", 'role': 'assistant'}]