You are presented with the question "Which is immobile?" and the following answer choices: 
- adult starfish
 - all matter
 - adult goldfish
 - gastropod shells
 - tadpoles
 - adult sponges
 - an object
 - an organism's body

Now knowing that adult sponges are sessile and sessile Attached permanently, immobile, choose the best answer.


 

      adult sponges   