19. A company's weighted average cost of capital should be calculated using A. before tax costs. B. after tax costs. C. before tax costs for debt but after tax costs for preferred stock and equity. D. either before or after tax costs. 20. In general, assuming that a firm's investment alternatives are not mutually exclusive, the firm should accept all projects A. for which it can obtain financing. B. that have a positive net present value. C. that have positive cash flows. D. that provide returns greater than the after tax cost of debt