The anal canal:

A、 Demonstrates an abrupt change in epithelial structure at the pectinate (dentate) line
B、 Has anal cushions lying distal to the pectinate (dentate) line
C、 Has circular and longitudinal muscle fibres
D、 Has fibres from the sacral sympathetic outflow to cause internal sphincter contraction
E、 Is supplied by branches of the inferior mesenteric and internal iliac arteries