Chapter 2: Cost behaviour and cost classification 2018 18. The following table detai ils the total cost Y, a stepped-fixed cost, for different production levels of Product X. Units of Product X 0 10 20 30 40 Cost Y ($000) 100 100 100 150 150 What could have been the cause of the increase in the cost? A. Increased storage requirements B. Pay increase for direct labour C. Loss of material discounts D. Increased fuel and maintenance costs for delivery vehicles