An investor purchases one municipal bond and one corporate bond that pay rates of return of 10% and 11.5%, respectively. If the investor is in the 20% tax bracket, his after-tax rates of return on the municipal and corporate bonds would be, respectively, _____.
A.10% and 11.5%
B. 12.00% and 9.20%
C. 10% and 9.20%
D. 8.00% and 11.5%