The kidneys perform several important functions in the human body. One of these is to regulate the amount of water that makes up the liquid part of blood. If too much water is present, the kidney will increase the amount of urine produced and lower the amount of liquid water in the blood. If the amount of water is too low, the kidney will decrease the amount of urine produced in order to conserve water
To test the responsiveness of the kidneys, scientists have designed an experiment tracking urine output of people during a normal day, while regulating the in-take of water by mouth. What would be an appropriate hypothesis for this experiment?

A. The amount of urine produced is dependent on the time of day.
B. The lower the volume of water in-take, the lower the volume of urine produced.
C. The greater the amount of physical activity during the day, the less urine produced.
D. The amount of urine produced is dependent on the relationship between air temperature and body temperature.