You are presented with the question "What do all vertebrates have?" and the following answer choices: 
- sensory neurons
 - characteristics
 - a complete digestive system
 - Veins and arteries.
 - sub-units of species
 - wings and feathers
 - gills
 - gizzard

Now knowing that chordates have a complete digestive system and a closed circulatory system and all chordates are vertebrates, choose the best answer.


 

   a complete digestive system      