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

Fact 2: Predators kill and eat their prey.

Given the two facts above, answer the question "What threat would cause a porcupine to extend its quills?" with the following options: 
- snow
 - killing insects
 - being eaten
 - wind
 - rain
 - threatened
 - sea urchins
 - opossums


 

   being eaten      