Correct Answer: A

Rationale: A bone marrow aspirate is the definitive test to confirm acute lymphoblastic leukemia (ALL) in this case. It allows for the examination of leukemic cells in the bone marrow, providing a direct assessment of the disease. Red blood cell count (Choice B) is not specific for diagnosing leukemia but may show anemia commonly seen in leukemia patients. Lumbar puncture (Choice C) is used to assess central nervous system involvement, not primarily for confirming ALL. Bone scan (Choice D) is not a standard diagnostic test for ALL and is mainly used for evaluating bone metastases in other conditions.

Correct Answer: C

Rationale: Eye drops should be placed in the conjunctival sac, which allows the medication to be absorbed properly without causing irritation. Placing drops directly on the sclera or near the lacrimal duct is less effective and can cause discomfort.

Correct Answer: A

Rationale: Gently tapping over the site helps dilate the veins and increase visibility. Applying a cold compress or raising the extremity above the body level constricts the veins, making them harder to access. Prolonged tourniquet use can cause discomfort and venous congestion.

Correct Answer: C

Rationale: Fever and general malaise are systemic signs of bacteremia, indicating that the infection may have spread beyond the local entry site. Localized pain, redness, and swelling are signs of a localized infection but do not necessarily indicate bacteremia.

Correct Answer: D

Rationale: Anaphylactic shock is a severe allergic reaction that causes massive vasodilation and increased capillary permeability, leading to rapid fluid shifts and circulatory collapse if not treated promptly. Neurogenic, cardiogenic, and hypovolemic shocks have different etiologies.