Which parts are included in the excretory system?

The excretory system's primary function is to remove waste products from the body and maintain a balance of bodily fluids. The components included in the correct answer consist of the kidneys, ureters, bladder, and urethra.

The kidneys filter blood to create urine, which contains waste substances and excess water. The ureters are tubes that carry urine from the kidneys to the bladder, where it is stored until it can be excreted. Finally, the urethra is the passage through which urine leaves the body. This system is crucial for regulating water, electrolyte balance, and the elimination of metabolic waste, which is vital for maintaining homeostasis in the body.

In contrast, the other options consist of different body systems. The heart, arteries, veins, and capillaries belong to the circulatory system, responsible for transporting blood and nutrients. The mouth, esophagus, stomach, and lungs relate to the digestive and respiratory systems, involved in nutrient intake and gas exchange, respectively. The brain, nerves, and spinal cord are part of the nervous system, responsible for processing information and coordinating responses. Each option highlights different body functions, but only the third option pertains specifically to the excretory system.