Final answer:
Urine is the fluid that contains urea, water, and salts and is released through the urethra. It is a byproduct of the body secreted by the kidneys and contains waste components.
Step-by-step explanation:
The fluid that contains urea, water, and salts that is released through the urethra is urine. Urine is a liquid byproduct of the body secreted by the kidneys. It is mainly composed of water but also contains nitrogenous molecules such as urea, as well as other metabolic waste components. Urine is collected in the ureters and stored in the urinary bladder before being excreted through the urethra.