Fact 1: Most invertebrates have a nervous system.

Fact 2: Insects are the most common invertebrates.

Given the two facts above, answer the question "What has a nervous system?" with the following options: 
- animals
 - tortoises
 - crocodiles
 - sponges
 - elephants
 - placozoans
 - mesozoans
 - insects


 

        insects 