Final answer:
The statement that if fluid intake equals fluid output, the total amount of water in the body will not change is true, as this represents a state of water balance essential for maintaining homeostasis.
Step-by-step explanation:
If fluid intake equals fluid output, then the total amount of water in the body will not change. This statement is true.
Water balance in the body is achieved when water intake, through drinking, eating, and metabolic processes, equals water output, which occurs via urine, sweat, feces, and evaporation. The kidneys play a vital role in maintaining this balance by regulating urine concentration. Homeostasis requires that water intake and output be balanced to maintain proper bodily functions.
Hormones like ADH (antidiuretic hormone) and aldosterone assist in the regulation of water and electrolyte balance by influencing water reabsorption in the kidneys. Therefore, if the intake of fluids is matched by the output, there will be no change in the total water content of the body.