In most regions of the GI tract (exceptions are oral cavity and stomach), smooth muscle fibers of the muscularis are arranged into:
a. inner circular and outer longitudinal layers.
b. outer circular and inner longitudinal layers.
c. circular and longitudinal layers whose relative position varies from region to region.
d. an interwoven meshwork of circular and longitudinal muscle fibers.
e. bundles aligned along three mutually perpendicular directions.