Maximal expiratory flow rates decrease during exhalation (i.e.,in going from higher to lower lung volumes)for the following reasons:

A)Intra-airway pressures increase and elastic recoil pressure increases at lower lung volumes.
B)Intra-airway pressures decrease and elastic recoil pressure increases at lower lung volumes.
C)Intra-airway pressures increase and elastic recoil pressure decreases at lower lung volumes.
D)Intra-airway pressures decrease and elastic recoil pressure decreases at lower lung volumes.
E)There is no change in intra-airway pressures or elastic recoil pressures at lower lung volumes.