It has to do with something about your brain, but I think its because people are afraid they did something wrong or mess up when they are speaking. It just reacts to your feelings. If you had practiced a lot, you probably won't be nervous, you will be confident.
I believe, the answer is; the sentence about teens also have is part-time. That could further the need of cars, because parents could be working full-time.
Middle Paragraphs, as they tend to makeup the majority of the essay.
