Answer:
The correct answer is: water.
Explanation:
Homeostasis is the state in which the body maintains itself in order to operate at its fullest, and for this to happen there are some factors that the body needs to regulate at all times: body temperature, pH, ion concentration, among others.
Osmotic balance ensures the concentration of electrolytes and non-electrolytes in the different compartments of the body: intracellular, extracellular, inside the plasma.
Since osmotic balance is achieved by regulating the filtration and absorption of water, it is very important for the systems in charge of homeostasis to control this aspect. For example, when there's water loss because of heavy exercise, the anterior pituitary gland releases ADH, a hormone that will act on the kidney to produce the reabsorption of water and avoid dehydration.