Which of the following best describes the function of hormones like ADH and aldosterone?

Hormones like antidiuretic hormone (ADH) and aldosterone play crucial roles in maintaining the body's fluid balance and urine composition. ADH primarily acts on the kidneys to promote water reabsorption in the collecting ducts, which helps to concentrate urine and reduce water loss. This hormone responds to increased blood osmolality, signaling the kidneys to retain water.

Aldosterone, on the other hand, is involved in regulating sodium and potassium levels. It stimulates the reabsorption of sodium and the excretion of potassium in the distal tubules and collecting ducts of the kidneys. This not only affects the volume of urine produced but also contributes to blood pressure regulation by influencing fluid balance.

Together, these hormones adjust urine volume and composition in response to the body's hydration status and electrolyte balance, making option B the best descriptor of their functions. The other choices either narrow the function too much, like solely altering blood pressure or decreasing kidney metabolism, or misrepresent the role of these hormones entirely, like suggesting they filter waste from the blood, which is primarily the function of the kidneys themselves rather than a hormonal action.