A nurse is assisting with the care of a client who is placed on supplemental oxygen for hypoxia. The nurse should identify that which of the following findings indicate the intervention was effective?

A. Restlessness is a common early sign of hypoxia. If the client remains restless despite supplemental oxygen, it suggests that oxygenation has not yet normalized. B. A respiratory rate of 28/min is above the normal adult range (12–20/min), indicating that the client may still be experiencing respiratory distress or inadequate oxygenation. C. Pink mucous membranes indicate adequate arterial oxygen saturation and tissue perfusion, showing that the supplemental oxygen is effectively reversing hypoxia and supporting cellular function. This is a key objective measure of oxygen therapy effectiveness. D. A heart rate of 110/min (tachycardia) may represent a compensatory response to hypoxia. If heart rate remains elevated, it may indicate that the oxygen therapy has not fully stabilized the client’s oxygenation.