The correct answer is: mucosa
The alimentary canal or gastrointestinal tract consist of four layers: mucosa, submucosa, muscular layer and serosa.
Mucosa is the layer that surrounds the lumen, so it is exposed to the food . Mucosa is composed of epithelium (active in absorptive and secretory processes), lamina propria (connective tissue) and muscularis mucosa (peristaltic movement).