Final answer:
Establishing and enforcing inner and outer perimeters around the incident scene substantially improves accountability, security, and force protection, by controlling access and maintaining order.
Step-by-step explanation:
The question relates to actions that can improve accountability, security, and force protection. Among the available options, establishing and enforcing inner and outer perimeters around the incident scene is the action that would best accomplish these goals.
This measure helps to manage the access to the scene, keeping unauthorized personnel out, and ensuring that only those with a legitimate role in managing the incident or conducting investigations are present. Such control of access points is crucial for maintaining order and security at an incident site.