Final answer:
Step-variable costs are costs that follow a step-cost behavior with narrow steps and increase or decrease in fixed increments within a certain range of activity.
Step-by-step explanation:
Step-variable costs are costs that follow a step-cost behavior with narrow steps. These costs increase or decrease in fixed increments within a certain range of activity.
For example, if a manufacturing plant requires one additional worker for every 100 units produced, the cost of labor would be a step-variable cost, as the cost would remain constant until the production exceeds the threshold for adding another worker.