Which of the following is a function of the kidneys?

The filtration of blood is a primary function of the kidneys and a crucial part of maintaining homeostasis in the body. The kidneys filter waste products, excess substances, and toxins from the bloodstream, effectively clearing these potentially harmful elements. This filtration process also helps to balance electrolytes and fluid levels, which are essential for the overall health of an individual. The kidneys are able to separate necessary substances from waste, allowing for their reabsorption back into the bloodstream as needed.

In addition to filtration, the kidneys play roles in hormone production and regulation of blood pressure as well, but the fundamental and most recognized function is their role in filtering blood to eliminate waste and maintain the body's internal environment.