9) Give an example of how a manager can increase variable costs while decreasing fixed costs. a. Hiring a subcontractor to do repairs on an annual retainer basis rather than on a per-visit basis b. Subcontracting a component to a supplier on a per-unit basis to avoid purchasing a machine with a high fixed amortization cost c. Changing a sales force compensation plan from a percent of sales dollars to a fixed salary d. None of the above