Which of the following does not have an anterior and posterior end?
Options:
- (A) Adult mammals
- (B) Adult reptiles
- (C) Adult birds
- (D) Adult echinoderms
- (E) Earth orbiting the Sun
- (F) an erupting volcano
- (G) peachleaf willow
- (H) sensory neurons Let's solve this problem gradually.

user
Adult echinoderms have radial symmetry. Animals with radial symmetry lack an anterior and posterior end. Adult echinoderms lack an anterior and posterior end. So the final answer is (D).
assistant