Answer:
The correct answer is: A) increases water reabsorption in the collecting tubule of the kidney.
Step-by-step explanation:
Antidiuretic hormone (ADH), also known as vasopressin, is an hormone synthesized in the hypothalamus.
ADH acts on 1) the kidneys (increases water reabsorption) and 2) the blood vessels (constricts arterioles, which increases blood pressure).
ADH is secreted when the plasma osmolarity increases (this means that the plasma is more concentrated than it should be, so the water reabsorption helps the plasma to return to its original osmolarity). ADH secretion can also be stimulated by a decrease in blood pressure.