A nurse is assessing a client after administering IV vancomycin. Which of the following findings is the nurse's priority to report to the provider?

The correct answer is B: Audible inspiratory stridor. This finding is indicative of a potentially serious adverse reaction known as anaphylaxis, which requires immediate medical intervention. Stridor suggests upper airway obstruction that can lead to respiratory distress and compromise the client's airway. Reporting this symptom promptly is crucial to prevent further complications. Choices A, C, and D are less urgent and can be addressed after ensuring the client's airway is stable. A headache, tinnitus, and localized redness are common side effects of vancomycin and can be managed with appropriate interventions.