A 20-year old man presents with pain and swelling about the left knee for the past month. He thought that this condition resulted from an old football injury and that it would resolve without incedent. The pain however has persisted and is severe enough to cause him to limp. Radiograph of the knee demonstrate a lifting of the periosteneum and a spiculatedsunburst pattern in the distal femur. Which of the following is the most likely diagnosis?

A) Osteosarcoma
B) Chondrosarcoma
C) Ewing sarcoma
D) Giant cell tumor