Would each of the following increase, decrease, or have an indeterminant effect on a firm's break-even point (unit sales)? a. The sales price increases with no change in unit costs. b. An increase in fixed costs is accompanied by a decrease in variable costs. c. A new firm decides to use MACRS depreciation for both book and tax purposes rather than the straight-line depreciation method. d. Variable labor costs decline; other things are held constant