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

Fact 2: Insects are the most common invertebrates.

Given the two facts above, answer the question "What do insects lack?" with the following options: 
- sensory neurons
 - the body's largest organ
 - a vertebral column
 - wings
 - legs
 - Chlorophyll
 - a cuticle
 - reproductive system


 

   a vertebral column      