What happens to the courtesy runner if they violate substitution rules?

In instances where a courtesy runner violates substitution rules, they are removed from the game and declared out. This rule ensures that players adhere to established guidelines regarding substitutions and gameplay. The courtesy runner is specifically designated to assist a player, typically one who is unable to run due to injury or other reasons. When this player does not comply with the rules, the enforcement of the penalty—removing them and declaring them out—maintains the integrity of the game. This process keeps the competition fair and upholds the regulations set forth by the governing bodies. Other options, such as the runner being replaced or receiving a warning, do not adequately address the seriousness of the violation in the context of game rules.