The answer is letter A.
The kidneys play a large role in filtration and in
the homeostasis of the body. They are two-bean shaped organs that filter the
blood, balance the fluids in the body, and form urine for excretion. They are
located against the back muscles in the upper abdominal cavity. When the kidney
has high concentrations of salts and less water it tends to develop kidney
stones, a condition that involves surgery for treatment. Dialysis is also a known
treatment to an injury or a disease that affects the kidney.
