You are presented with the question "Sea creatures encased by what reproduce sexually?" and the following answer choices: 
- barnacles
 - refraction of light
 - layers of fat
 - Epidermis
 - tough membranes
 - ocean water
 - gastropod shells
 - epidermis and dermis

Now knowing that tunicates reproduce sexually and tunicates are sea creatures encased by tough membranes, reminiscent of tunics, choose the best answer.


 

     tough membranes    