A worker who can be counted on to complete assigned tasks without constant supervision is said to have:

Having reliability means that a worker consistently completes assigned tasks efficiently and can be counted upon to meet expectations without the need for continual oversight. This trait is critical in any workplace, as it fosters trust between employees and management. Reliable workers contribute to a team's overall productivity and morale, allowing for smoother operations since colleagues and supervisors can depend on them to fulfill their responsibilities.

The other options reflect important workplace traits but do not specifically address the ability to work independently without supervision. Poise relates to maintaining composure in challenging situations, adaptability refers to the capacity to adjust to change or new conditions, and perseverance signifies the commitment to continue pursuing goals despite obstacles. While each is valuable in their own right, they do not directly capture the essence of being dependable in task completion as reliability does.