"Removing all cancer cells without surgery." Surgical treatment is a primary approach in managing Osteosarcoma.

The goal of surgery is not to remove cancer cells without surgery but to remove the tumor and surrounding affected tissues while preserving the affected limb whenever possible.

Complete removal of all cancer cells is challenging with surgery alone, which is why other treatments like chemotherapy are often used in conjunction.

Choice C rationale:

"Administering radiation therapy only." While radiation therapy may be used as part of the treatment plan for Osteosarcoma, it is not the primary goal of surgical treatment.

Surgical intervention, such as limb-sparing surgery or amputation, is the mainstay of therapy for Osteosarcoma.

Choice D rationale:

"Performing amputation as the primary treatment." While amputation may be necessary in some cases of Osteosarcoma, the primary goal of surgical treatment is to preserve the affected limb whenever possible.

Amputation is considered when limb preservation is not feasible or when the tumor is very large and invasive.