What is a vertical lifeline system primarily used for?

A vertical lifeline system is primarily designed to secure a harness to a stable anchor point, enabling the wearer to safely work at heights while preventing falls. The system consists of a durable line that runs vertically and is anchored at the top. This setup ensures that, in the event of a fall, the worker's harness is securely connected, minimizing the risk of injury.

While the other options might pertain to fall protection in different capacities—for instance, providing a means of descent or assisting in load distribution—they do not specifically describe the main function of a vertical lifeline system. Its primary role focuses on securing the worker effectively to a fixed point, which is critical for safety in telecommunications installations and maintenance.