Which Statement About Respiratory Adaptations Is True

Which statement about respiratory adaptations is true?

A) Respiratory surfaces in all animals require ventilation.
B) External gills are found only in invertebrates.
C) Most fishes ventilate their gills by swimming almost constantly with their mouths open.
D) In fish, water flows unidirectionally into the mouth, over the gills, and out from under the opercular flaps.
E) Desiccation of the respiratory surface is more likely to occur in gills than in lungs.