Answer:
The mucosa, or mucous membrane layer.
Explanation:
It is the innermost tunic of the wall. It lines the lumen of the digestive tract. The mucosa consists of epithelium, an underlying loose connective tissue layer called lamina propria, and a thin layer of smooth muscle called the muscularis mucosa.
Hope I helped! :)
.
Hippocrates the ancient famous philosopher taught his students that food is medicine.