What do echinoderms lack?\nOptions:\n- (A) Lungs\n- (B) Mass\n- (C) oxygen\n- (D) eardrum\n- (E) gills\n- (F) ovaries\n- (G) Organs\n- (H) Bodies
Hmmm, let me think. I don't want to be wrong, so I got to be careful.
User
Echinoderms lack respiratory and excretory systems. Lung mechanics and gas exchange are topics during study of the respiratory system. Echinoderms have no lungs. The answer: (A).
Assistant