An 18-year-old client is diagnosed with mononucleosis and manifests left upper quadrant tenderness and an enlarged spleen. Which is the most important teaching that the practical nurse (PN) should offer this client?

A. Gargle with warm salt water: Helps sore throat but not most urgent. B. Avoid exposing older client to complications: Not related to spleen risk. C. Stay home and isolate for two weeks: Good infection control but not most critical. D. Use stool softeners to prevent Valsalva maneuver: Valsalva increases intra-abdominal pressure and risk of splenic rupture.