问题如下：
The analysis performed by Sardar on the Purity Fund can be best described as being based on:
选项：
A.a holdings-based approach
manager self-identification
a returns-based style analysis.
解释：
A is correct. Dewey asks Sardar to perform a bottom-up style analysis of thePurity Fund based on the aggregation of attributes from individual stocks in
the portfolio, which describes a holdings-based approach to style analysis. The
overall equity investment style is an aggregation of attributes from individual
stocks in the portfolio, weighted by their positions.
想延伸下本题目请教下老师，case文章最后说到“ Dewey plans to include the results of this style analysis in a profile he is preparing for the fund.” 这是否代表其实也应用了一些risk-based 方法？
如果有选项是tranction based（也就是结合了return-based 和holding-based 方法的第三种方法），是不是应当选这个选项？
