You're asking about the organ responsible for excretion in humans. That organ is the kidney.

Here's why:

* Excretion is the process of removing waste products from the body.

* The kidneys filter blood and produce urine, which contains waste products like urea, excess water, and salts.

* The urine then travels through the ureters to the bladder, where it's stored until it's expelled from the body.

While other organs like the lungs, skin, and liver also contribute to excretion, the kidneys are the primary organs responsible for filtering waste from the blood.