Which statement is not true concerning the anal canal?
A.
It is about 1/2 inches (3.8 cm) long.
B.
It pierces the urogenital diaphragm.
C.
It is related laterally to the external anal sphincter.
D.
It is the site of an important portal-systemic anastomosis.
E.
The mucous membrane of the lower half receives its arterial supply from the inferior rectal artery.