A. Increase the oxygen flow rate: The patient’s SpO₂ of 88% indicates hypoxemia (goal usually ≥92% for most patients); the immediate nursing action is to increase oxygen delivery (e.g., raise the nasal cannula flow) to improve oxygenation while reassessing. B. Document the current oxygen saturation: Documenting is important, but it is not the first action when the patient is hypoxemic - intervention to correct the low saturation should come first. C. Call the respiratory therapist for an assessment: Useful if you need help or advanced adjustment, but calling RT delays the immediate intervention; first attempt simple measures (increase flow, reposition, confirm cannula placement) and then request RT if saturation does not improve. D. Reassess the oxygen saturation in 30 minutes: Waiting 30 minutes without intervening is unsafe for a patient with SpO₂ 88%; reassessment should be immediate after interventions, not delayed.