The mechanism whereby buoyancy is achieved in different kinds of fishes is: ___________

a. All of the choices are methods for achieving buoyancy.
b. through the presence of a large, oily liver when a swim bladder is not present.
c. None of the choices are correct.
d. through the presence of a swim bladder that is kept filled as the fish periodically swims to the surface and gulps air.
e. through the presence of a swim bladder that is regulated internally by structures that add or remove air from the bladder by capillary beds.