Answer:
Aldosterone.
Explanation:
Aldosterone is a hormone that regulates the levels of sodium and potassium in our body, which leads to regulate our fluid levels.
In order to increase the fluids in our system, aldosterone causes the absorption of sodium from our kidneys. The kidneys are the place where our body filters the blood absorbing what it needs, such as sodium, and excreting the rest as urine. With the entering of sodium to our bloodstream, water also enters, increasing the volume of blood in our body.
Aldosterone is also responsible for the excretion of potassium into the urine, controlling the levels of this ion, which is extremely important for a high number of reactions.
