12 . The after -tax cost of debt generally increases when :" I . a firm's bond rating increases . II . the market - required rate of interest for the company's bonds increases . III. tax rates decrease . IV . bond prices rise . A . I and !IT only B. II and III only C. I, II, and III only D. II , III, and IV only E . I, II, III , and IV F. None of the above