What is the primary purpose of a stopper knot when tied to the end of a rope?

The primary purpose of a stopper knot is to prevent equipment from sliding off the end of the rope, which is fundamental in various rescue scenarios and other applications involving ropes. When the knot is tied securely, it creates a physical barrier that ensures any load or equipment attached to the rope remains in place and does not fall off accidentally. This is vital in rescue situations, where any loss of gear or equipment could pose serious safety risks.

While other choices may seem relevant, they do not align with the fundamental function of a stopper knot. For instance, the knot does not inherently create hitches for climbing, enhance aesthetic appearances, or serve as an anchor attachment mechanism. Each of these has specific knots designed for those purposes, but a stopper knot primarily focuses on preventing unwanted movement of the rope's end.