What term is used to describe the point in time when a contingency plan will be implemented?

The term that describes the point in time when a contingency plan will be implemented is known as a "Trigger." This is the specific event or condition that prompts the execution of the contingency plan. Triggers are essential in project management because they define clear parameters for action in response to unforeseen circumstances or risks that could affect project outcomes. By identifying triggers, teams can ensure they are prepared to respond quickly and effectively, minimizing potential disruptions to the project.

In contrast, checkpoints refer to scheduled assessments throughout the project to review status and performance, milestones mark significant points of progress within a project timeline, and event horizon typically pertains to a theoretical boundary in physics, not specifically related to project management processes. Therefore, the use of the term "Trigger" captures the critical aspect of readiness for action when specific risk situations arise, making it the correct answer.