What is the primary function of the stomach?

The primary function of the stomach is to store food and begin the digestion process. When food enters the stomach, it is temporarily held in a muscular pouch where it is mixed with gastric juices. These juices contain hydrochloric acid and digestive enzymes that start breaking down proteins and killing harmful bacteria. This process transforms the food into a semi-liquid substance called chyme, which gradually empties into the small intestine for further digestion and nutrient absorption.

While bile is involved in digestion, it is stored in the gallbladder, not the stomach. Insulin is produced by the pancreas, and nutrient absorption mainly occurs in the small intestine, rather than the stomach. Thus, the correct answer highlights the stomach's role in both storing food and initiating the digestion process.