Choice A rationale:

 Palpating the lymph nodes.

Rationale: Palpating the lymph nodes is relevant because it helps assess for potential metastasis.

Osteosarcoma can spread to nearby lymph nodes, and checking for enlarged or palpable lymph nodes is important in assessing the extent of the disease.

Choice B rationale:

 Measuring blood pressure.

Rationale: Measuring blood pressure is generally not directly relevant to assessing Osteosarcoma.

While hypertension can be a side effect of some cancer treatments, it is not a primary assessment for Osteosarcoma itself.

Choice C rationale:

 Assessing range of motion of the affected limb.

Rationale: Assessing range of motion of the affected limb is relevant because Osteosarcoma can cause pain, swelling, and limitations in joint mobility.

Evaluating the range of motion helps in assessing the impact of the tumor on the patient's functional status.

Choice D rationale:

 Inspecting the skin for changes in color or texture.

Rationale: Inspecting the skin for changes in color or texture is relevant because skin changes, such as erythema (redness), warmth, or ulceration, can be indicative of advanced disease or tumor extension into the soft tissues surrounding the bone.

Choice E rationale:

 Evaluating the patient's cognitive function.

Rationale: Evaluating the patient's cognitive function is generally not directly relevant to assessing Osteosarcoma.

It may be important for other conditions or as part of a comprehensive patient assessment but is not specific to Osteosarcoma.