The nurse is caring for a 13-year-old who is 2 days post-operative from a laparoscopic appendectomy. Upon assessment, the nurse notes the following vital signs: 37,1°C (98.8°F), a pain rating of 3 out of 10, and breath sounds are diminished in the lower lobes. What action should the nurse take first?

A. Prone positioning is not recommended post-operatively for abdominal surgery and could exacerbate respiratory issues. B. While monitoring white blood cell count is important, encouraging lung expansion and preventing complications such as atelectasis is a more immediate priority. C. The client's pain rating is low and does not necessitate immediate administration of acetaminophen. D. Encouraging the use of an incentive spirometer helps improve lung expansion, which is crucial to prevent atelectasis and promote proper oxygenation, particularly when breath sounds are diminished.