What is a key characteristic of a personal fall arrest system?

A personal fall arrest system is designed specifically to protect workers from the risk of falling while working at heights. Its primary function is to safely catch and secure the worker if they do lose their footing, thereby preventing serious injuries or fatalities associated with falls. This system typically includes components such as a harness, lanyard, and anchor point, all of which work together to maintain a secure connection to a structural support, ensuring the worker’s safety during their tasks.

While it's true that these systems may allow for a certain degree of movement, the key characteristic lies in their protective capability against falls. The other options do not capture the essence of a personal fall arrest system's primary purpose, which is centered around the prevention of injuries from falls. Proper use and regular inspection of these systems are critical components of ensuring safety in various work environments, and they are applicable beyond just ladder work, further reinforcing the importance of the protective aspect highlighted in the correct answer.