Which of the following tumor is the most chemoresistant?

Malignant fibrous histiocytomas are derived from fibroblast. The typical age at presentation is between 50 and 70 years. They present with pain, with or without a palpable mass. Radiographically, a mass is usually evident, with destruction of surrounding tissue and bone. Treatment is wide resection with a margin of >=4 cm and reconstruction. The use of chemotherapy is considered controversial in patients with malignant fibrous histiocytoma. Rhabdomyosarcomas are sensitive to chemotherapy and often are treated with preoperative chemotherapy. Because of the poor prognosis, the treatment plan of synol sarcoma should include aggressive wide resection, along with both radiation therapy and chemotherapy. Osteosarcoma is radioresistant; radiation therapy has no role in the routine management. Preoperative chemotherapy followed by limb-sparing surgery (which can be accomplished in >80% of patients) followed by postoperative chemotherapy is standard management. Ref: Randall R.L., Hoang B.H. (2006). Chapter 6. Musculoskeletal Oncology. In H.B. Skinner (Ed), CURRENT Diagnosis & Treatment in Ohopedics, 4e.