What Do Postural Drainage, Positive Expiratory Pressure Therapy, Autogenic Drainage

What do postural drainage, positive expiratory pressure therapy, autogenic drainage, forced expiration techniques, and high-frequency chest compressions have in common?

A) They dislodge mucus from the bronchial walls of patients.
B) They attempt to prevent dynamic airway collapse.
C) They work toward increasing the functional residual capacity of patients.
D) They are intended to promote the ability of patients to generate effective coughs.