Fact 1: Threatening behavior by predators causes a porcupine to extend its quills.

Fact 2: Puffers are smooth skinned while Porcupines have the characteristic spines or quills.

Given the two facts above, answer the question "What does a porcupine do with its spines when it's threatened?" with the following options: 
- killing insects
 - Shoot them
 - kill them
 - protect them
 - Extend them
 - Shed them
 - Retract them
 - behave


 

     Extend them    