The correct option is A Osmoregulation
Osmoregulation in humans refers to the regulation of water in the body. ADH or antidiuretic hormone or vasopressin is a hormone produced by the hypothalamus, and released in high doses when the water level in the body is low. ADH signals the kidneys to absorb a lot of water back into the body to form concentrated urine. When the water level in the body is high, lower doses of ADH get released into the bloodstream, signalling the kidneys to excrete highly dilute urine and reabsorb less water into the body.