The correct option is C Aldosterone
Aldosterone (salt-retaining hormone) regulates the sodium content of the body. It is secreted when the sodium level is low. It acts on the kidneys to cause more sodium to be returned to the blood and potassium to be excreted. As the sodium concentration in the blood increases, water follows it by osmosis, so the blood volume also increases. Thus, the effect of aldosterone is reabsorption of both sodium and water in the blood.