What is the primary function of the urethra?

The primary function of the urethra is to transport urine from the bladder to the exterior of the body. It acts as a conduit through which urine is expelled during urination. In males, the urethra also has the additional function of carrying semen during ejaculation, but its fundamental role in both sexes is the passage of urine.

In contrast to the other functions listed, filtering blood is a critical function of the kidneys, as they cleanse the blood and remove waste products, which are then processed into urine. The production of urine itself occurs in the kidneys, where the filtration process takes place. Absorbing nutrients is primarily the role of the intestines in the digestive system, not the urethra. Thus, focusing on the correct role of the urethra clarifies why it is responsible specifically for the transportation of urine.