Which device is commonly used to aid in descending during rope rescue?

The belay device or rappel device is specifically designed to facilitate safe and controlled descent during a rope rescue. These devices allow the rescuer to manage the rope's friction which can be adjusted to control the speed of descent effectively. When using a belay or rappel device, the rescuer can maintain a secure grip on the rope while ensuring they can stop or slow the descent as needed, providing a critical safety feature during rescue operations.

In contrast, a carabiner, while important for connecting components in a rope system, does not provide any mechanism for controlling descent. A pulley system is typically used for lifting or changing the direction of the rope but does not assist directly in descending. Lastly, a harness system is vital for securing the rescuer or victim, but it does not offer the means to control descent on its own. Each of these devices plays an important role in rescue operations, but the belay or rappel device is essential for the safe management of descending.