You are presented with the question "some what lack respiratory systems?" and the following answer choices: 
- Smoking
 - respiratory systems
 - deuterostomes
 - cigarettes
 - alpacas
 - hawks
 - barnacles
 - pigs

Now knowing that echinoderms lack respiratory and excretory systems and all echinoderms are deuterostomes , choose the best answer.


 

   deuterostomes      