Answer:
d. an onblique muscle layer
Explanation:
The alimentary canal has four main layers:
Mucosa (innermost layer which surrounds the lumen), submucosa (connective tissue with blood vessels, lymphatics, and nerves), muscular layer, serosa ( outermost layer of connective tissue).
Muscular layer is subdivided into:
• the inner- arranged in circular rings, prevents food from travelling backward
• outer layer- arranged longitudinally, shortens the tract.
The stomach has an extra layer called inner oblique muscular layer (churning function).
