Threatening behavior by predators causes a porcupine to extend its quills, and puffers are smooth skinned while Porcupines have the characteristic spines or quills. Given these facts, what does a porcupine do with its spines when it's threatened among the following options:
- killing insects
 - Shoot them
 - kill them
 - protect them
 - Extend them
 - Shed them
 - Retract them
 - behave


 

     Extend them    