Which of the Following Statements Is Correct, Other Things Held

Which of the following statements is correct, other things held constant?

A) Firms whose assets are relatively liquid tend to have relatively low bankruptcy costs; hence, they tend to use relatively little debt.
B) An increase in the personal tax rate is likely to increase the debt ratio of the average corporation.
C) An increase in the company's degree of operating leverage is likely to encourage a company to use more debt in its capital structure.
D) An increase in the corporate tax rate is likely to encourage a company to use more debt in its capital structure.