The answer is (c) excretion
The human excretory system consists of two kidneys, two ureters, a urinary bladder, and a urethra. There are two kidneys in the abdomen, one on each side of the vertebrae. The urinary bladder is where the urine that is produced in the kidneys is stored until it is released through the urethra. Urine travels through the ureters into the bladder.