The After-Tax Cost of Debt Generally Increases When

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 III 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.