Which of the Following Findings Indicates to the Nurse That

Which of the following findings indicates to the nurse that a patient with acute respiratory distress who has no history of chronic lung disease is in acute respiratory failure?

A) pH of 7.34
B) Arterial partial pressure of oxygen (PaO₂) of 45 mm Hg
C) Arterial partial pressure of carbon dioxide (PaCO₂) of 50 mm Hg
D) Evidence of respiratory muscle fatigue