According to your textbook, what kind of supporting materials is used in the following speech excerpt:

Imagine this: You have spent most of the night studying for an exam. But when you get up the next morning ready to take the test, you go to your front door and it won't open. So you head to the back door, and it won't open either. You are stuck in the house. It would be pretty frustrating, wouldn't it? This is exactly the kind of frustration wheelchair-bound students feel when they can't get to class because of the snow.