Answer:
An oblique muscle layer.
Explanation:
Stomach is one of the most important organ involved in the process of digestion. The initiation of the protein digestion occurs in the stomach and the acidic environment of the stomach kills the harmful bacteria.
The whole area of the alimentary canal longitudinal layer of the muscle and the circular layer of the muscle. The stomach also contains the additional layer known as the oblique muscle layer that is used for the wringing for itself during food processing.
Thus, the correct answer is option (1).