麻烦老师解释一下第四小题的解题思路和答案，谢谢

问题如下：

Testing whether there is a change in the money supply growth after the shift in policy, using a 0.05 level of significance, we conclude that there is:

选项：

A.sufficient evidence that the money supply growth changed B.not enough evidence that the money supply growth is different from zero C.not enough evidence to indicate that the money supply growth changed

解释：

The null hypothesis of no difference in the annual growth rate is rejected at the 0.05 level: The calculated test statistic of −8.16188 is outside the bounds of ±2.048.