The nurse has just received arterial blood gas (ABG) results on four patients. Which result is most important to report rapidly to the health care provider?

pH 7.31, PaO2 91 mm Hg, PaCO2 50 mm Hg, and O2 sat 96%

pH 7.34, PaO2 85 mm Hg, PaCO2 40 mm Hg, and O2 sat 97%

pH 7.46, PaO2 89 mm Hg, PaCO2 32 mm Hg, and O2 sat 98%

pH 7.35, PaO2 85 mm Hg, PaCO2 45 mm Hg, and O2 sat 95%