This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metastatic Bone Disease, Subject name: Orthopaedics
[{'content': 'Most common soft tissue tumor in a child: \nSelect and explain. \nA. Rhabdomyosarcoma, B. Histiocytoma, C. Fibrosarcoma, D. Liposarcoma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (a) Rhabdomyosarcoma- Rhabdomyosarcoma, the most common childhood soft-tissue sarcoma, is often located in the head and neck (40%) and in the trunk and extremities (25%).', 'role': 'assistant'}]