What should a referee do when time remains and a player who committed an offense is still unsubstantiated?

A referee must prioritize the fairness and integrity of the game, which includes addressing offenses committed by players on the field. When a player commits an offense and is unsubstantiated while there is still time remaining in the match, the referee's responsibility is to assess the appropriate penalty for the violation. This approach ensures that the game is managed according to the established rules and that players are held accountable for their actions.

Assessing the penalty may involve awarding a free kick or a penalty kick, depending on the nature and severity of the offense, which helps uphold the rules governing fair play. In some cases, this could also mean reducing the number of players on the field for the offending team—making them "play short" for a period of time. This response reinforces the idea that violations will be addressed promptly, thereby maintaining the competitive balance of the match.

The other choices lack this focus on enforcing the rules comprehensively. Allowing a player to continue without addressing an offense (the first choice) undermines the authority of the referee and sets a poor precedent for player conduct. Issuing a warning (the second choice) does not adequately reflect the seriousness of the offense and may diminish the perceived significance of rule enforcement. Waiting until the game stops (the last choice