You are presented with the question "What organisms are a source of food for many species of fish?" and the following answer choices: 
- remains of prehistoric life
 - whales
 - organic matter
 - sharks
 - gastropod shells
 - those on the ocean floor
 - Something made from fermented ricce
 - humans

Now knowing that sponges are a source of food for many species of fish and like sponges, they are attached to the ocean floor, choose the best answer.


 

      those on the ocean floor   