13. What is an example of sunk cost? a) future cost of buying a train ticket b) machine already purchased c) the parking cost you would need to pay d) fixed costs 14. Accepting a special order will improve overall net operating income if the revenue from the special order exceeds: a) the contribution margin on the order. b) the incremental costs associated with the order. c) the variable costs associated with the order. d) the sunk costs associated with the order