For what purpose are red signal streamers primarily used?

Red signal streamers are primarily used to warn individuals of entering a live-fire area. This is critical for maintaining safety on the range, as it alerts personnel to the potential dangers associated with live ammunition and ongoing shooting activities. The vivid color of the signal streamers enhances visibility and ensures that everyone in the vicinity is aware that they are approaching an area where firearms are in use, thereby helping to prevent accidents and promote safe practices.

In contrast, the other options do not align with the primary function of red signal streamers. While they may address various safety or directional needs in various contexts, only the use of red signal streamers as a warning for live-fire areas directly corresponds to established range safety protocols.