What is the first line of defense for a property?

The correct answer emphasizes the importance of the property's borders as the first line of defense. The borders serve as the initial physical barrier that can deter unauthorized access, protecting what lies within. This could include fences, walls, gates, or the overall perimeter of the property. By clearly defining the limits of the property, these boundaries can reduce the likelihood of intrusion and theft, setting the stage for subsequent layers of security.

While other options may play significant roles in overall security, they typically follow the borders in the hierarchy of protective measures. For instance, security personnel and interior controls are critical but are more effective when a solid and well-maintained perimeter is established first. The walls of the building offer protection, but they are not as effective without the preliminary deterrent of secure borders.