In Planning Care for the Patient with Cystic Fibrosis (CF),the

In planning care for the patient with cystic fibrosis (CF) ,the nurse understands that which of the following interventions is the most important therapeutic approach to promote pulmonary function in the patient?

A) Regular administration of bronchodilators
B) Administration of continuous low-flow oxygen
C) Maintenance of prophylactic doses of antibiotics
D) Chest physiotherapy every 4 hours to mobilize secretions