A nurse is caring for a patient on a mechanical ventilator. Which intervention is most effective in preventing Ventilator-Associated Pneumonia (VAP)?

✓ Correct Answer: Option B

Elevating the head of the bed to 30-45 degrees (semi-Fowler's position) helps prevent aspiration of oropharyngeal secretions and gastric contents into the lungs, significantly reducing the risk of VAP. Other options are incorrect or not most effective.