Correct Answer: A

Rationale: The primary advantage of prescribing rivaroxaban over warfarin for a patient with a history of deep vein thrombosis (DVT) is that rivaroxaban does not require regular INR monitoring. This eliminates the need for frequent blood tests to adjust the dosage, making it more convenient for patients to manage their anticoagulant therapy.

Correct Answer: C

Rationale: In children, ringing in the ears (tinnitus) can be a sign of aspirin toxicity. Aspirin toxicity can be particularly concerning in children and can lead to serious complications. Therefore, it is crucial for the nurse to prioritize monitoring for signs of aspirin toxicity, such as tinnitus, and promptly notify the healthcare provider if such symptoms occur.

Correct Answer: C

Rationale: The correct instruction for a patient prescribed metformin is to take the medication with meals. This helps reduce gastrointestinal side effects commonly associated with metformin. Patients should also be educated about the signs of lactic acidosis, a rare but serious side effect associated with metformin use.

Correct Answer: B

Rationale: The correct answer is B: Liver toxicity. Valproic acid is known to potentially cause liver toxicity. Monitoring liver function tests regularly in patients taking valproic acid is crucial to detect any signs of liver damage early and prevent serious complications.

Correct Answer: A

Rationale: To calculate the dosage, first, convert the weight from pounds to kg (4 lbs / 2.2 ≈ 1.82 kg). Then, multiply by the prescribed mg/kg (15 mg/kg * 1.82 kg ≈ 27.3 mg). However, since the question asks for the closest correct option, the infant will receive approximately 9 mg.