In Aquatic Vertebrates,which Kidney Function Is Critical to Helping the Organism

In aquatic vertebrates,which kidney function is critical to helping the organism maintaining homeostasis?

A) The kidneys function to maintain the balance between water and several types of salts.
B) The kidneys produce a concentrated form of urine that will help decrease the amount of water lost by the organism.
C) The kidneys have an incredible high rate of tubular reabsorption that allows them to be extremely efficient.
D) The kidneys are relatively small and only require a limited blood supply to maintain their function.
E) The kidneys will produce white blood cells that will assist the organism in defense of the body.