When should secondary responders enter an area believed to be occupied by friendly forces?

The most appropriate answer is based on the critical importance of ensuring safety and coordination among responders during a chaotic situation like an active shooter incident. Entering an area occupied by friendly forces requires a clear understanding of the situation on the ground to prevent confusion and potential friendly fire incidents.

The correct choice emphasizes that secondary responders should wait until a positive "Link-up" has been made. This means that they should have confirmation of the presence of friendly forces, their location, and the overall situation before entering the area. Establishing clear communication and visual identification helps to ensure that responders can effectively coordinate their efforts without the risk of mistakenly targeting each other.

This approach minimizes the potential for miscommunication and enhances the safety of all individuals involved by ensuring that every responder is aware of who is present and the current operational dynamics. It creates a unified front in addressing the threat while preserving the safety of both civilians and the responders themselves.