d) The statement is incorrect as aquatic organisms use different methods of gas exchange, such as gills, lungs, and direct diffusion.
An aquatic organism is the one which is either vertebrate or invertebrate, that lives in the water for it's entire life. An aquatic organism respire by either of the specialized organs like gills, lungs, or by diffusion through skin.
Although gill like organs are located in different aquatic organisms such as a mollusks, insects, fishes, crustaceans and amphibians but not all aquatic organisms such as diatoms and other zooplanktons do not exhibit gills they respire by simple diffusion process.
Therefore, All aquatic organisms have gills as part of their respiratory system is incorrect.
