Fact 1: Invertebrates are animals that lack a vertebral column, or backbone.

Fact 2: Snails and slugs are invertebrates.

Given the two facts above, answer the question "what do snails and slugs lack?" with the following options: 
- eyes
 - a nervous system
 - kinetic energy
 - Chlorophyll
 - Energy.
 - life
 - a backbone
 - Energy


 

       a backbone  