What happens if the referee observes an illegal replacement made by a libero?

The correct answer highlights the role of the scorer in ensuring the integrity of substitutions during a volleyball match. When a referee observes an illegal replacement made by a libero, the appropriate action involves the scorer notifying the referee about the violation. This is crucial because the libero has specific rules governing their substitutions, and any unauthorized substitution can affect the flow and fairness of the game.

Understanding this process is important because it emphasizes the collaborative effort in officiating, where the scorer's responsibility is to keep track of substitutions and notify the referee of any irregularities. This procedure helps maintain order and allows the match to proceed correctly while addressing the violation.