Which of the following statements is correct?

A. The appropriate tax rate to use in the adjustment of the before-tax cost of debt to determine the after-tax cost of debt is the average tax rate because interest is deductible against the company’s entire taxable income.

B. For a given company, the after-tax cost of debt is generally less than both the cost of preferred equity and the cost of common equity.

C. For a given company, the investment opportunity schedule is upward sloping because as a company invests more in capital projects, the returns from investing increase.