wrote:
Drinking is regulated by plasma osmolality and extracellular fluid volume in much the same way as vasopressin secretion.Thirst,thereford,is estimulated by aan increase in plasma osmolality and a decrese in plasma volume.
Vasopressin is often called the ADH.It increase the permeability of the collectin renal tubes.so the water enter the hypertonic intertitium of the renal pyramids.The urine becomes concentrated, and its volume decrease. The overall effect is thereford retention of water, and decrease in the osmolaslity of the body fluids.Thus,sensation of thirst is suppressed.

So answer is B as Bela.