这道题计算逻辑是什么？

问题如下：

An investor purchases a nine-year, 7% annual coupon payment bond at a price equal to par value. After the bond is purchased and before the first coupon is received, interest rates increase to 8%. The investor sells the bond after five years. Assume that interest rates remain unchanged at 8% over the five-year holding period. Assuming that all coupons are reinvested over the holding period, the investor's five-year horizon yield is closest to:

选项：

A.

5.66%.

B.

6.62%

C.

7.12%

解释：

Correct Answer: B