Imagine an Invertebrate That Lives in an Estuary Where Salinity

Imagine an invertebrate that lives in an estuary where salinity varies cyclically with the tides. If this individual is able to adjust the salt concentration of its body fluids, its salt concentration will have

A) slight fluctuations that are kept within a narrow range.
B) irregular fluctuations that range from large to small.
C) a cyclic fluctuation opposite that of the surrounding water.
D) a cyclic fluctuation depending upon when the animal drinks.