You are presented with the question "What lacks a centralized nervous system?" and the following answer choices: 
- Damaged hearing
 - Humans
 - Horses
 - Sand dollars
 - insects
 - Chickens
 - Pesticides
 - barnacles

Now knowing that echinoderms lack a centralized nervous system and sand dollars and sea biscuits are also echinoderms, choose the best answer.


 

    Sand dollars     