You are presented with the question "Starfish, sea urchins and sea cucumbers lack a what?" and the following answer choices: 
- characteristics
 - the body's largest organ
 - watery habitat
 - centralized nervous system
 - functioning arm
 - underwater life
 - biological diversity
 - epidermis and dermis

Now knowing that echinoderms lack a centralized nervous system and echinoderms include starfish, sea urchins, and sea cucumbers, choose the best answer.


 

    centralized nervous system     