Final answer:
The layers of the stomach and small intestine's wall from outermost to innermost are serosa, muscularis, submucosa, and mucosa.
Step-by-step explanation:
The correct order of the tissues composing the wall of the stomach and the small intestine from the outermost to the innermost layer is: serosa, muscularis, submucosa, and mucosa. The serosa is the outermost layer that is continuous with the mesentery. Just beneath the serosa lies the muscularis which includes a double layer of smooth muscle in the small intestine and an additional oblique muscle in the stomach. The submucosa is a layer of dense connective tissue that houses blood and lymphatic vessels as well as nerves. The mucosa is the innermost layer, and it is in contact with the digestive contents within the lumen of these organs.