A Patient Is 1 Day Postlumbar Fusion Surgery

A patient is 1 day postlumbar fusion surgery.Upon initial evaluation by the physical therapist,the patient was recorded to have an SpO₂ of 92% on 2 L of O₂ via a nasal cannula.The physical therapist suspects acute atelectasis due to postoperative pain.Of the following,which is the BEST immediate intervention to improve oxygenation in this patient?

A) Use of an incentive spirometry.
B) Teach the patient pursed lip breathing.
C) Encourage the patient to sit in a chair.
D) Use of a lumbar corset.