Assume that Lucas' marginal tax rate is 10% and his tax rate on dividends is 5%. If a dividend-paying stock (with no growth potential) pays an 5.6% dividend yield, what interest rate would a municipal bond have to offer for Lucas to be indifferent between the two investments from a cash-flow perspective?

a 10%

b 5.6%

c 5%

d 5.32%

e None of the choices are correct.