Which event exemplifies assault on a sports official?

The scenario where Dan punches the umpire after a bad call clearly exemplifies assault on a sports official. Assault in this context is characterized by intentionally causing physical harm to another person. In sports, officials such as umpires are designated authorities whose decisions are to be respected as part of the game. Physically attacking an official is a serious offense, not only because it violates the norms of sportsmanship but also because it poses a direct threat to the safety of individuals who serve in that capacity. This action may result in legal consequences, including charges of assault, as it involves intentional physical aggression directed at a person performing their duties within an official capacity.

The other options do not fit the criteria for assaulting an official in a sports context. The accidental discharge of a gun implies negligence rather than intent to harm, chasing a thief does not involve aggression towards an official, and flirting has no inherent connection to assault. Thus, Dan's action of punching the umpire clearly stands out as an instance of assault against a sports official.