Fact 1: Most invertebrates have a nervous system.

Fact 2: Invertebrates are animals without a backbone.

Given the two facts above, answer the question "Which type of system do most animals without backbones have?" with the following options: 
- sensory neurons
 - Veins and arteries.
 - Nervous system
 - Stereo system
 - Root system
 - to move people
 - Skeletal system
 - insects


 

   Nervous system      