The answer is (C) Low water concentration in blood; high water concentration in urine. ADH (antidiuretic hormone) is responsible for regulating water balance in the body. When there is not enough ADH, the kidneys are not able to reabsorb enough water, which leads to a high concentration of water in the urine and a low concentration of water in the blood. This can cause symptoms such as excessive thirst, dehydration, and frequent urination.