Who may replace the libero during a match?

The correct answer is that only the player whom the libero replaced may substitute in for the libero during a match. In volleyball, the libero has specific roles and limitations, one of which is that their substitution must follow a strict protocol. When the libero exits the court, they can only be replaced by the player who was originally in the position that the libero took over.

This rule is designed to ensure the integrity of the game and maintain the strategic aspect of player positions. The libero has unique abilities and restrictions that differentiate them from other players, and this replacement rule is reflective of that distinction. It allows coaches to manage their lineup while adhering to the regulations set forth by the sport's governing bodies.

The other options are incorrect because they do not align with the official rules concerning the libero's substitutions. For instance, allowing any team member who did not start would disrupt the tactical balance and position designations established at the start of the set. Similarly, allowing any player on the roster or only players who started the set would contradict the specific rules governing the libero’s role and its substitution process.