What is the main role of the stomach?

The stomach primarily serves the important function of storing and breaking up food. When food enters the stomach, it is mixed with gastric juices, which contain enzymes and acids. These substances help to chemically break down the food into a semi-liquid form known as chyme. The muscular walls of the stomach also churn and physically mix the food, enhancing digestion. This process not only aids in the breakdown of food particles but also prepares them for further digestion and nutrient absorption in the small intestine.

The other choices do not accurately describe the stomach's functions. For instance, the pumping of blood is the responsibility of the heart, while the lungs are involved in breathing. The removal of water from food is primarily a function of the large intestine.