Final answer:
Fixed ladders exceeding 24 feet in height must be equipped with personal fall arrest systems to ensure the safety of the users from falls.
Step-by-step explanation:
Fixed ladders that extend more than 24 feet must have D) Personal fall arrest systems rather than cages or wells to protect users from fall hazards. Personal fall arrest systems typically include a full-body harness, lanyard, connectors, and a suitable anchor point that can support the forces of a fall. These systems are designed to safely stop a fall before the worker hits a lower level, thus reducing the risk of serious injury.