In the game of tennis, a "service fault" occurs when the serve does not land in the correct area of the service box.
Among the options provided, the correct example of a service fault is:
C. the ball hits the net and lands outside of the service box.
This is because a serve that hits the net and doesn't land within the service box is considered a fault. Options A and B could either be valid serves depending on the position of the ball in relation to the lines, and option D is a valid serve.