Garrett's teacher asked his class to write down every response they could think of to the question, "what would you do if you could be invisible for a day? " this kind of exercise fosters thinking.

The correct answer is divergent.
There are two types of thinking - convergent and divergent. Convergent thinking is more logical - we come up with various solutions to the problem, but usually only one of them is correct. On the other hand, divergent thinking is more creative - it usually involves many solutions to the problem, and it is a spontaneous, brainstorming type of thinking. This is often used when writing, whereas convergent thinking is used in math and logic.