Postural Drainage Is BEST Defined by Which of the Following

Postural drainage is BEST defined by which of the following statements?

A) Rhythmical clapping with cupped hands over the affected lung segment.
B) Clinician's hands are used to exert pressure on the patient's chest wall with oscillations at the end of deep inspiration through expiration.
C) The assumption of one or more body positions that allow gravity to assist with draining secretions from each lung segment.
D) A series of maneuvers performed by the patient to emphasize independence in secretion clearance and thoracic expansion.