Suppose the interest rate is 6% for a municipal bond and is 8% for a corporate bond. If an investors marginal tax rate is 25%, which of the following statements is correct?

A. Municipal bond offers a higher after-tax rate of return

B. Corporate bond offers a higher after-tax rate of return

C. Municipal bond and corporate bond have the same after-tax rate of return

D. Insufficient information to determine which bond offers a higher after-tax rate of return