When is the timekeeper instructed to hold time?

The correct choice indicates that the timekeeper is instructed to hold time when an umpire whistles an infringement. This is essential because stoppages in play caused by infringements directly affect the flow of the game and the regulation of time. Holding time allows for the game to maintain its integrity by ensuring that no additional time is lost during these interruptions.

In netball, the game proceeds continuously except for specific interruptions, and accurate timekeeping is crucial. When an umpire blows the whistle for an infringement, they often call for the play to stop immediately, thus necessitating that the timekeeper pause the game clock to reflect the actual time spent on the court. This ensures fairness and accuracy in the timing of each quarter.

The other options, while related to the game's flow and time management, do not represent the primary responsibility of the timekeeper in relation to holding time during events of disruption or play stoppage. For example, after a goal is scored, play generally resumes without needing the timekeeper to halt the clock. Player substitutions typically occur without stopping time either, and while the end of each quarter is significant, the role of the timekeeper at that moment is more about signaling rather than actively holding time.