What marks the transition from reactive to proactive incident management?

The transition from reactive to proactive incident management is marked by the incident briefing. This stage is crucial because it allows for a comprehensive overview of the incident and serves as a platform for command personnel to gather information, share strategies, and establish a unified approach to managing the incident. Through the incident briefing, effective communication is fostered among responders, which enhances situational awareness and prepares the team to take proactive measures in managing the incident rather than merely reacting to it as it unfolds.

In stark contrast, the other options focus on different aspects of incident management. For instance, incident size-up involves assessing the situation and identifying hazards, which is essential but primarily reactive in nature. Incident stabilization focuses on controlling the emergency once it has already developed, and initial response pertains to the first actions taken upon arriving at the scene. While all these elements are vital for effective incident management, they do not embody the proactive planning and strategy that the incident briefing represents.