You are presented with the question "Coral reefs are made up of the exoskeletons of thousands of what?" and the following answer choices: 
- Absorb light
 - scarce resources
 - Chlorophyll
 - tiny polyps
 - to stay warm
 - animals
 - salt and water.
 - graptolites

Now knowing that many corals secrete an exoskeleton that builds up to become a coral reef and coral is made of the exoskeletons of many thousands of tiny marine animals called polyps, choose the best answer.


 

    tiny polyps     