问题如下：
Which of the statements about the relationship between the performance of mutual fund managers and passive index strategy is correct?
选项：
A.The performance of mutual fund managers is equal to a passive index strategy.
B.The performance of mutual fund managers may outperform a passive index strategy.
C.The performance of mutual fund managers may underperform a passive index strategy.
解释：
C is correct.
Research shows that the passive index strategy is superior to the performance of most mutual fund managers.
老师请问，如果没有市场有效性作为前提，就选C的话，那为什么人们要去买mutual fund而不去选择被动投资呢？
