A Spontaneously Breathing Patient Has the Following Arterial Blood Gas

A spontaneously breathing patient has the following arterial blood gas results: pH 7.33, PaCO₂ 52 mm Hg, PaO₂ 56 mm Hg, F_IO₂ 60%. The best action to normalize the blood gas results is:

A) increase F_IO₂.
B) initiate CPAP.
C) initiate mechanical ventilation and pressure support.
D) initiate mechanical ventilation and PEEP.