Fact 1: Mollusks are invertebrates such as the common snail.

Fact 2: Invertebrates have no backbone.

Given the two facts above, answer the question "What do mollusks not have?" with the following options: 
- backbone
 - tissue
 - alveoli
 - life
 - heat energy
 - a cuticle
 - food
 - shell


 

 backbone        