What type of device is essential in a lowering system connected to an anchor?

In a lowering system, a braking device is essential because it allows for controlled descent and ensures the safety of the person being lowered. This device manages the speed at which the load is lowered and can help prevent accidents by stopping or slowing down the descent if necessary.

Braking devices are designed to handle dynamic loads, which are present when a person is being lowered. They typically engage to provide friction and control over the rope, making them vital for safe operations in rope rescue scenarios. They are crucial for balancing safety and efficiency during a rescue operation, allowing rescuers to lower individuals or equipment with precision.

The other options serve different roles that are not directly related to the function of lowering in a system. A fixed pulley primarily changes the direction of the force applied to the rope but doesn’t control the descent speed. A rescue harness is important for securing the individual being lowered, while a safety carabiner is essential for connecting various components but doesn't have a direct role in controlling the lowering process.