问题如下：
Dewey asks Sardar to perform a bottom-up style analysis of the Purity Fund based on the aggregation of attributes from individual stocks in the portfolio. Dewey plans to include the results of this style analysis in a profle he is preparing for the fund. 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-identifcation
a returns-based style analysis
解释：
A is correct. Dewey asks Sardar to perform a bottom-up style analysis of the Purity 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.
请问老师，这一道题，哪里显示是holding base 的方法了呢，谢谢
