Fact 1: Echinoderms lack a centralized nervous system.

Fact 2: Echinoderms include starfish, sea urchins, and sea cucumbers.

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


 

    centralized nervous system     