Place adjacent marking signs at intervals of ________ to ________ meters, depending on the terrain.

The correct range for placing adjacent marking signs during CBRN reconnaissance operations is 25 to 100 meters. This range is emphasized to ensure effective visibility and recognition of the markings without overwhelming the personnel or compromising the tactical situation. The distance is also influenced by factors such as terrain type and visibility conditions.

In areas with good visibility and less dense terrain, signs can be placed at longer intervals of up to 100 meters, allowing for efficient marking while maintaining safety and operational effectiveness. Conversely, in more challenging terrains or lower visibility conditions, signs would be placed closer together to ensure they remain discernible to those navigating the area.

The other ranges provided do not align with standard practices for CBRN reconnaissance marking. Specifically, intervals that are too short may lead to redundancy and clutter in certain environments, while intervals that are too long may reduce the effectiveness of marking in guiding personnel through hazardous areas.