For which of the following offenses can the referee take disciplinary action?

Unsportsmanlike conduct is considered a serious offense in soccer, as it undermines the spirit of fair play and respect among players, coaches, and officials. When a referee observes actions that fall under unsportsmanlike behavior—such as arguing with officials, taunting opponents, or using abusive language—they have the authority to take disciplinary action. This can include issuing a warning, a yellow card for a caution, or a red card for more severe infractions.

The other scenarios mentioned do not fall within actions that merit disciplinary measures. Failure to score is simply a part of the game and does not involve misconduct. Resetting the ball for a restart is a procedural aspect of officiating and does not inherently involve any player misconduct. Similarly, excessive duration of play pertains more to game management rather than to a player's conduct, and it often falls under the referee’s duties to manage time effectively without issuing disciplinary action. Thus, unsportsmanlike conduct is the only option from the list where the referee specifically has the authority to impose a disciplinary response.