题目：
An investor is considering the purchase of two bonds. One of the bonds is tax-exempt and yields 4.5% while the other bond is taxable and yields 6.0%. If the two bonds are alike in all other characteristics, the marginal tax rate that would make the investor indifferent between the two bonds is closest to:（）
A. 9.0%.
B. 25.0%.
C. 27.0%.
答案：
参考答案：B
解析：
Compute the after-tax yield of a taxable security and the tax-equivalent yield of a tax-exempt security. The indifference point would be the tax rate that satisfies the equation: 6.0%×(1- T)=4.5%. Solving for T, the marginal tax rate =25%.
