Which organ is responsible for excreting water and waste products?

The kidneys are the primary organs responsible for excreting water and waste products from the body. They perform a crucial function in the urinary system by filtering the blood, removing excess water, electrolytes, and toxic substances. This filtration process results in the formation of urine, which is then transported to the bladder for storage before being excreted.

The kidneys also play a vital role in maintaining homeostasis by regulating the body’s fluid balance, electrolytes, and blood pressure. This ability to concentrate or dilute urine allows the kidneys to efficiently manage and excrete waste based on the body's hydration levels.

While the liver does process and detoxify substances in the body, its primary function is not directly related to the excretion of water and waste in the same way the kidneys function. The intestines are primarily involved in digestion and absorption of nutrients rather than excretion. The bladder, on the other hand, stores urine produced by the kidneys but does not play a role in the filtering and excretion process itself. Thus, the correct choice, the kidneys, directly correlates to their essential function in waste management and fluid regulation in the body.