Final answer:
The only essential stomach function necessary to life is the production of intrinsic factor for the absorption of vitamin B12 (option b). Other functions, like food storage and acid secretion, are not critical as long as B12 absorption can occur through alternative means such as injections.
Step-by-step explanation:
The only stomach function that is essential to life is the production of intrinsic factor. Intrinsic factor is a glycoprotein that the stomach lining secretes, and it is necessary for the intestinal absorption of vitamin B12. Without vitamin B12, our bodies can't produce mature red blood cells or maintain normal neurological functioning.
Although the stomach does have other functions such as food storage, secretion of gastric acids and enzymes, and absorption of certain drugs, these are not critical to life. For instance, people who undergo total gastrectomy can still survive if they receive vitamin B12 injections, which bypasses the need for the stomach's intrinsic factor.
When you eat food, absorption occurs primarily in the small intestine. The nutrients from the food are absorbed into the bloodstream through the walls of the small intestine after being digested by the stomach and mixed with digestive juices to form chyme.