A Fish Swimming into an Estuary from a River Would

Multiple Choice

A fish swimming into an estuary from a river would have which of the following as its greatest physiological challenge?

A) The high water flow would make the fish expend more energy.
B) The low oxygen content would give the fish difficulty in swimming aerobically.
C) The temperature change would stress the fish by denaturing its proteins.
D) The change in water solute content would challenge the osmotic balance of the fish.