问题如下：
Knight foresees a possible scenario in which the investment universe for the Heydon Quant Fund is unchanged but a new factor is added to its multifactor model. Knight asks Nowacki whether this scenario could affect the fund’s investment-style classifcations using either the returns-based or holdings-based approach. The most appropriate response to Knight’s question regarding the potential future scenario for the Heydon Quant Fund is:
选项：
A.only the returns-based approach
only the holdings-based approach
both the returns-based approach and the holdings-based approach
解释：
C is correct. Because the Heydon Quant Fund would be changing its facto rmodel by adding a new factor, the correlations of the fund’s returns with the factors would likely change and the returns-based style would change. Even though the investment universe is unchanged, the portfolio holdings would likely change and the holdings-based style classifcation would also will be affected.
关于这道题我有个问题：
按照老师例题的讲解。holding方法是时点观察，如果加入新的factor，那么组合立刻会变，所以holding肯定受影响。
但是return方法是平均值啊， 如果加入新的factor，就算组合立刻变，但是平均整个时期，受影响有限啊。
为什么答案是两个都受影响？
