After Instructing the Patient in Using the Incentive Spirometer (IS)

After instructing the patient in using the incentive spirometer (IS) , the nurse instructs nursing assistive personnel (NAP) to encourage the patient to use it.What does the nurse provide to the NAP as a rationale for using the IS after surgery?

A) It helps to maintains venous return.
B) It helps prevent atelectasis and pneumonia.
C) It prevents any type of respiratory infection.
D) It strengthens the lungs for recovery.