Final answer:
Raising their quills helps porcupines defend themselves from predators.
Step-by-step explanation:
The behavior of raising their quills helps a porcupine defend itself from predators. When a porcupine feels threatened, it raises its quills to make itself look larger and more intimidating. The quills are sharp and barbed, making them difficult to remove once they embed in a predator's skin or mouth. This defense mechanism helps the porcupine survive and reduces the chances of being preyed upon.