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: Pathology
[{'content': 'Commonest sarcoma in children is - \nSelect and explain. \nA. Rhabdomyosarcoma, B. Lipoma, C. Angiosarcoma, D. Fibrosarcoma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Rhabdomyosarcoma\n\nCommonest sarcoma in children is rhabdomyosarcoma.\nIt is a tumour of Primitive mesodermal origin.\nThe most common site is head and neck.\nThe genitourinary region is the second most common site.\nOther sites are extremities and retroperitoneum', 'role': 'assistant'}]