The correct answer is (c) Excretory system.
The kidney regulates the excretory system of the body. The excretory system of the body is responsible for the excretion of harmful waste from the body.This function of discharging waste out of the body is called urination. By this the body maintains homeostasis. The human body has two kidneys. The blood arrives to the kidney, where the waste are taken are taken out by the process of filtration. After the filtration process the urine is collected for sometime in urethra which is expelled out when the urethra is full. If this function is not carried out properly then many diseases associated with excretory system takes place such as kidney stone, hematuria, nephritis.
