why isn't B? clear explanation please

5. (A) (B) Which of the following is true about the WACC? When computing the weights for different source of capital, the book values are preferable to the market values. Cost of debt is the ratio of interest expense in the income statement to the total amount of debt outstanding. The effect of taxes increases the cost of debt and makes debt financing less attractive for corporations. The cost of equity reflects the riskiness of the project. (C) (D)