Physical activity reduces stress because it helps get your brain moving and doing something other than the anxieties and stress. When your active you are more focused on the thing your doing rather than the stressor/s. It has also been proven that sitting and stressing makes it worse so to move your mind off it for a hit helps you to relax and also gives your brain time to think things out.
I think 1,2,and,4 are true
Social anxiety disorder is interesting, I have it, its a common one in teens.
