酸、碱、盐在溶液中进行的复分解反应，如果有_________，或有__________，或有____________，这时复分解反应就可以发生，否则就不能发生。

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 yield 6.0%. If the two bonds are alike in all other characteristics, the rate that would make the investor indifferent between the two bonds is closest to:（）

A. 9.0%.

B. 25.0%.

C. 27.0%.