This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Tumors, Subject name: Orthopaedics
[{'content': "Tumour most sensitive to radiotherapy is \nSelect and explain. \nA. Osteogenic sarcoma, B. Ewing's sarcoma, C. Multiple myeloma, D. Osteoclastoma", 'role': 'user'}, {'content': "Answer: B \nExplanation: EWING'S SARCOMA: This is highly malignant tumour occurring between the age of 10-20 years, sometimes up to 30 years. This is a highly radiosensitive tumour, melts quickly but recurs. In most cases, distant metastasis has occurred by the time diagnosis is made. Treatment consists of control of local tumour by radiotherapy (6000 rads), and control of metastasis by chemotherapy. Chemotherapy consists of Vincristine, Cyclophosphamide, and Adriamycin in cycles repeated every 3-4 weeks for about 1218 cycles. Reference: Maheshwari; Essential Ohopaedics; Page no: 243", 'role': 'assistant'}]