Answer:
The correct answer would be a kidney.
A kidney is a bean-shaped organ present in a pair in vertebrates.
The main function of the kidney is the filtration of the blood which leads to the production of urine.
Kidney consists of millions of nephrons (structural and functional unit of a kidney) which help in filtration, reabsorption, secretion, and excretion.
Filtration is the process by which large substances such as proteins, cells et cetera are retained while smaller molecules are filtered which constitute the ultra-filtrate. It takes place at renal corpuscle.
Kidney generates around 180 liters of filtrate in a day out of maximum amount is reabsorbed by other parts of the nephron.