A Patient Being Mechanically Ventilated Is Prescribed Peak End-Expiratory Pressure

A patient being mechanically ventilated is prescribed peak end-expiratory pressure (PEEP) .How does this setting assist the ventilated patient?

A) It delivers a breath only if the patient does not breathe spontaneously.
B) It provides positive pressure on expiration to keep small airways open.
C) It delivers a breath in a set pattern regardless of the patient's respiratory pattern.
D) It provides positive pressure on inspiration and expiration to increase oxygenation.