It can filter less water out of the blood is the right answer.
On a normal day, the normal adult will use in approximately 2500 mL of aqueous liquids. Although the maximum of the absorption appears through the digestive system, roughly 230 mL per day is produced metabolically, in the last actions of aerobic inhalation. Moreover, the body leaves the same amount of water in different ways. However, during periods of heavy sweating, kidneys also can regulate blood volume through mechanisms that bring water out of the urine and filtrate.