What is the most logical next event?

A young teenaged boy is standing outside of the house with a tennis ball and racket. He goes to the tennis court and begins to talk about the game of tennis. he

OPTIONS: I. goes and retrieves the ball and continues talking about it.; II. serves the tennis ball back and forth between the two young men, and backs them forward all the way.; III. does some stretches for a little but and then gets ready to hit the ball over to the other side of the court.; IV. stops for a moment to explain that the ball is used mostly in the backyard, which includes several tennis courts to play in.;
III.