Variable costs are usually characterised by: (a) Unit costs that decrease as activity increases. (b) Total costs that increase as activity decreases. (c) Total costs that increase as activity increases. (d) Total costs that remain constant. 3 Marks 13. Margin of safety is: (a) Another name for marginal cost (b) The difference between fixed cost and marginal cost (c) The same thing as contribution margin (d) The difference between actual or expected sales and the break-even sales 3 Marks 14. Stepped costs are usually characterised by: (a) Total costs that increase as activity increases. (b) Total costs that do not change steadily as activity changes, but rather at discrete points. (c) Total costs that remain constant (d) None of the above