Final answer:
In emergency medical services, the scene size-up involves establishing the cause for the call (option 2), ensuring safety, and preparing for patient care. Determining the cause for the call to the scene is one of the three basic goals, as it helps assess and manage the emergency effectively.
Step-by-step explanation:
In emergency medical services (EMS), the scene size-up is a critical component of the initial response to a medical call. One of the basic goals of scene size-up is to determine what led to your being called to the scene (option 2). This entails understanding the nature of the emergency situation, and potential hazards present, and gathering initial information that could impact patient care and responder safety.
Determining whether the patient is breathing may occur shortly after scene size-up but is not one of the three initial goals. While assessing the patient's chief complaint and medical history are also important, they come into play after the scene has been deemed safe and the EMS providers move on to patient assessment, which includes taking a history and performing a physical examination.
The three core objectives of the scene size-up can be summarized as ensuring scene safety, establishing the mechanism of injury or nature of the illness, and determining the number of patients and the need for additional resources. Knowledge and application of these objectives can potentially save lives by enabling responders to act efficiently and appropriately during an emergency.