What is the purpose of a stopper knot in a descent line?

The purpose of a stopper knot in a descent line is to indicate the end of the line. This function is critical for safety and usability. When using a descent line, particularly in climbing, rescue scenarios, or industrial applications, the stopper knot serves as a visual and tactile cue that signifies the termination of the rope. This helps the user understand that they should not attempt to descend further past the knot, ensuring that they remain safely within the confines of the usable length of the rope.

This clear differentiation prevents accidents that could occur if a user mistakenly thought there was more rope available for descent. Additionally, the knot increases the chance of the line being effectively anchored at one end, providing safety through an unmistakable endpoint that is easily recognizable.

The other options do not accurately describe the primary function of a stopper knot in a descent line, emphasizing the importance of recognizing the correct application of knots in safety-critical environments.