What characterizes a compound system in rope rescue?

A compound system in rope rescue is characterized by the configuration where a simple system is used to pull on another simple system. This arrangement allows for an increased mechanical advantage compared to using a single simple rigging setup. By combining two or more systems, rescuers can distribute the load more effectively and manage heavier weights or provide greater lifting capabilities.

This layering of systems enables the rescuer to achieve the necessary lift with less force applied to the rope, making it easier to rescue an individual from a confined space. The interactions between the two simple systems contribute to an overall increase in efficiency and effectiveness during the rescue process.

The other options do not accurately capture the essence of a compound system. For instance, while multiple pulleys can be part of a compound system, simply using multiple pulleys without indicating the connection to another simple system does not define the compound nature. Additionally, the mechanical advantage beyond 4:1 isn't a defining characteristic of a compound system itself, as various configurations can achieve different advantages without relying solely on that ratio.