What functions do the kidneys perform?

The kidneys play a crucial role in maintaining the body’s internal environment through their ability to regulate fluid levels and filter blood. They are responsible for removing waste products and excess substances from the bloodstream, which helps to regulate the composition of blood, including electrolytes, pH levels, and fluid balance.

This filtration process occurs in the nephrons, the functional units of the kidneys, where blood is filtered, and urine is produced. Additionally, the kidneys help control blood pressure by managing the volume of fluids in the body and releasing hormones that influence blood vessel constriction.

The other options pertain to functions that are not performed by the kidneys. For instance, creating blood cells is primarily the function of the bone marrow, while breaking down nutrients is a role of the digestive system. Producing bile is a function of the liver, not the kidneys. Therefore, the correct choice reflects the specialized functions of the kidneys in the context of maintaining homeostasis in the body.