The esophagus has several variations from the standard plan of the GI tract. These include

A) epithelium of mucosa is stratified squamous.
B) epithelium of mucosa is simple columnar.
C) muscularis externa has some skeletal muscle.
D) epithelium of mucosa is stratified squamous and simple columnar.
E) epithelium of mucosa is simple columnar and muscularis externa may be striated muscle.