What must be used to protect every raising system, regardless of complexity?

The option that should be used to protect every raising system, regardless of its complexity, is a ratchet. A ratchet provides a mechanical advantage and secures the load by preventing it from slipping back. In any raising system, maintaining control and ensuring safety is paramount, and a ratchet accomplishes this by allowing for secure tensioning of the rope, which is essential in various rescue scenarios. The mechanism of a ratchet helps to manage heavy loads safely and efficiently, reducing the risk of accidents during lifting operations.

While other items have their specific uses in rope rescue, such as ensuring personal safety or securing connections, the ratchet serves as a critical component for the control of loads in any raising system. It is tailored to enhance both function and safety across a wide variety of applications.