You are presented with the question "fish, amphibians, reptiles, birds, and mammals have what?" and the following answer choices: 
- food
 - fur and fat
 - backbone
 - power
 - four limbs
 - retina
 - vision
 - competition

Now knowing that vertebrate chordates have a backbone and chordates Chordates Chordates include fish, amphibians, reptiles, birds, and mammals, choose the best answer.


 

   backbone      