Final answer:
The initial responding officer defines the perimeter by considering the primary focal points, avenues of entry and exit, and secondary scenes that are crucial for the integrity and security of the crime scene.
Step-by-step explanation:
When an initial responding officer arrives at a crime scene, one of their first duties is to establish a perimeter. This is essential for preserving the integrity of the crime scene and securing it from potential contamination. The correct answer to the question is b: Primary focal points, avenues of entry and exit, and secondary scenes. These are critical considerations for an officer when securing a crime scene.
The primary focal point is usually where the central incident took place, such as the location of a robbery or assault. Avenues of entry and exit are vital in understanding potential paths the suspect or suspects may have used to arrive at or leave the scene, as well as for determining possible escape routes. Lastly, identifying any secondary scenes is crucial, as these could include locations where additional evidence may be found or areas where the perpetrator may have prepared or disposed of something related to the crime.