The main responsibilities of an incident commander are:

• A. Spotting emergency vehicles at the incident and directing rescue
• B. Controlling all radio communications and developing SOP's
• C. Controlling the incident, observing, and talking with the media
• D. Size-up and developing an incident action plan

Answer: (D)

The main concept tested here is that the incident commander’s primary duty is to size up the scene and develop an incident action plan to guide the response. Size-up means quickly assessing hazards, conditions, risks to responders, and resource needs, while continually updating this understanding as the incident evolves. The incident action plan translates that assessment into clear objectives, strategies, and assignments for all teams and units, ensuring coordinated effort, safety, and effective use of resources. While other tasks like directing specific actions, managing communications, or handling public information are important, they support the overarching process of understanding the situation and laying out a concrete plan to achieve priorities. This makes size-up paired with an incident action plan the best answer.