An investor buying a municipal bond and a corporate bond is offering a pre-tax return of 7.50% and a municipal bond has a pre-tax yield of 8.75%, respectively. If the investor has a marginal tax rate of 30%, the after-tax rate of return on this investor's corporate bonds would be:

a.

6.56%

b.

7.50%

c.

5.85%

d.

6.13%