If reptiles are a class of tetrapod vertebrates that produce eggs with a waterproof shell, then reptiles are a class of tetrapod vertebrates that produce eggs with a what?

Answer choices:
- kinetic energy
 - Chemical energy
 - the body's largest organ
 - heat energy
 - Epidermis
 - epidermis and dermis
 - waterproof shell
 - rapid expansion

 

       waterproof shell   