An investor in the 28% tax bracket is considering buying one of the following securities: A fully taxable Treasury security offering a 6.0% yield. A municipal bond offered at par offering a 4.0% yield. What is the after-tax yield on the Treasury and the taxable-equivalent yield on the municipal bond After-tax yield on the treasury Taxable-equivalent yield on the municipal（）

A. 4.32%                2.88% 

B. 4.32%                5.56% 

C. 6.48%                2.88%