Answer: B. Step costs
Explanation: Step costs cannot be accurately represented by a single straight line. This is because of its unusual step-like manner—horizontally over a range, then vertically, then horizontally, and so on. Step costs are expenses that change disproportionately when production levels or activity levels of any firm, increases or decreases—they are constant for a given level of activity, but increase or decrease once a threshold is crossed.
Step costing is very important when a company is about to achieve a new and higher activity level or if activity is falling off and operations must be reduced.