Which of the following statements is MOST correct? A. There is no reason to think that changes in the corporate tax rate would affect firms' capital structure decisions. B. A firm with high business risk is more likely to increase its use of financial leverage than a firm with low business risk, assuming all else equal. C. If a firm's cost of equity exceeds its cost of debt, it can always reduce its WACC by increasing its use of debt. D. In general, a firm with low operating leverage also has a small proportion of its total costs in the form of fixed costs