You are presented with the question "Lungs are used for breathing air by animals with what?" and the following answer choices: 
- unidirectional
 - exoskeleton
 - contracting
 - fins
 - four limbs
 - gills
 - kinetic energy
 - eight eyes

Now knowing that lungs are used for breathing air by land animals and land Animals Land animals have four limbs, choose the best answer.


 

     four limbs    