According to the Modigliani and Miller prop. I with corporate taxes and with bankruptcy costs _____________________________. A) bankruptcy costs as well as debt tax shield are zero B) the value of the firm is independent of its capital structure C) the required return on equity initially increases as debt-to-equity ratio rises and then declines after the optimum debt to equity ratio is reached D) at the point where the debt amount maximizes the value of the firm, the increase in the present value of bankruptcy costs from an additional dollar of debt is equal to the increase in the present value of the debt tax shield