Variable cost per unit a. All of these answer choices are correct. b. increases on a per unit basis when the level of activity increases. C. can be estimated by performing break-even calculations. d. is represented by the slope of the total cost line. A cost center a. is responsible for generating profit. b. should be evaluated using return on investment to best motivate managers. C. places its managers responsible for all costs under their control. d. requires a set of performance measures that are more complex than those for an investment center. In deciding whether to sell or process further, the costs that have been incurred to process the product to the split-off point are incremental costs. a. TRUE b. FALSE