During the set, the libero tracker shall:
Notify the second referee if the libero does not remain out of the set for one rally between replacements, unless the libero is replacing the player in the right back position and will serve the next rally.
Inform the second referee of each teams libero status at the beginning of each time-out.
Notify the scorer to sound the audio device at the time the ball is contacted for the serve when there is an illegal replacement.
All are correct.
(D) All are correct.
Explanation: