Chemotherapy is often used in the treatment of Osteosarcoma to help prevent the spread of cancer cells, which is known as metastasis.

Osteosarcoma has a tendency to metastasize to the lungs and other bones, and chemotherapy is administered to target and kill any remaining cancer cells that may have spread beyond the primary tumor site.

Therefore, the nurse's response that chemotherapy helps prevent metastasis is appropriate and educates the patient about one of its key purposes.

Choice A rationale:

"Chemotherapy helps reduce emotional distress" is an inaccurate statement.

While chemotherapy can be emotionally distressing due to its side effects, its primary purpose is to treat cancer by targeting and destroying cancer cells.

Managing emotional distress may be a part of supportive care but is not the main rationale behind chemotherapy.

Choice C rationale:

"Chemotherapy targets osteosarcoma cells directly" is not entirely accurate.

While chemotherapy does target cancer cells, it does not specifically target only Osteosarcoma cells.

It affects rapidly dividing cells, which includes both cancerous and some healthy cells, leading to various side effects.

The primary purpose of chemotherapy in Osteosarcoma is to prevent metastasis and shrink or eliminate the tumor.

Choice D rationale:

"Chemotherapy is used to manage pain" is not the main purpose of chemotherapy in Osteosarcoma.

Pain management is typically achieved through analgesics and other pain-relieving measures.

Chemotherapy may indirectly help with pain by shrinking the tumor and reducing pressure on surrounding tissues, but pain management is not its primary rationale.