How do marine and freshwater mollusks compare to terrestrial mollusks in their respiratory systems?
A- Marine and freshwater mollusks have gills on their radula whereas terrestrial mollusks have no radula.
B- Marine and freshwater mollusks have a primitive lung whereas terrestrial mollusks have gills.
C- Marine and freshwater mollusks have no gills whereas terrestrial mollusks have gills.
D- Marine and freshwater mollusks have gills whereas terrestrial mollusks have a primitive lung.
