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

Fact 2: Porcupine quills can be extraordinarily painful.

Given the two facts above, answer the question "What can threatening behavior be?" with the following options: 
- opossums
 - painful
 - imbalanced
 - tiny
 - threatened
 - smoking
 - comprehensive
 - funny


 

  painful       