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.
aggregation of attributes from individual stocks，这个说的不是把每个股票的return的贡献汇总起来吗？
