Which organs are part of the excretory system?

The choice identifying the kidneys, bladder, ureter, and urethra as part of the excretory system is correct because these organs work together to remove waste and excess substances from the body.

The kidneys filter blood to produce urine, which contains waste products and excess salts. The urine then travels through the ureters to the bladder, where it is stored until it is ready to be expelled from the body through the urethra. This system plays a crucial role in maintaining the body's fluid balance and ensuring that harmful substances are effectively eliminated.

In contrast, the other options include organs that do not belong to the excretory system. The heart and lungs are primarily involved in circulation and respiration, while the liver and pancreas are integral to digestion and metabolism. The stomach and intestines are also part of the digestive system, responsible for breaking down food and absorbing nutrients, rather than processing and eliminating waste. Thus, the correct answer highlights the specific organs that are functionally crucial for excretion.