The Muscularis Externa Contains Which of the Following Muscle Groups

Multiple Choice

The muscularis externa contains which of the following muscle groups?

A) a muscularis mucosae, which lubricates as it contracts
B) an outer longitudinal layer that requires neural input for contraction
C) an inner circular layer capable of slow- wave potentials only
D) both an inner circular and an outer longitudinal layer
E) an inner circular and outer longitudinal layer, and a muscularis mucosae