问题
单项选择题
Index funds are:（）
A. on average underpriced by 15%, but this underpricing varies over time, which supports the EMH.
B. on average overderpriced by 15%, but this overpricing varies over time, which supports the EMH.
C. security portfolios designed to duplicate the composition and therefore the performance of a selected market index series.
答案
参考答案：C
解析：
Index funds are security portfolios designed to duplicate the composition and therefore the performance of a selected market index series.