West Corporation has $50,000 that it plans to invest in marketable securities. The corporation is choosing between the following three equally risky securities: Alachua County tax-free municipal bonds yielding 8.00%; Exxon Mobil bonds yielding 9.70%; and GM preferred stock with a dividend yield of 9.00%. West's corporate tax rate is 25.00%. What is the after-tax return on the best investment alternative? Assume a 50.00% dividend exclusion for taxes on dividends. (Assume the company chooses on the basis of after-tax returns. Round your final answer to 3 decimal places.)

a. 7.275%

b. 7.875%

c. 8.000%

d. 6.750%

e. 8.488%