这题不理解，请解释说明。

问题如下：

Which of the following is most consistent with a discretionary portfolio management approach to ESG integration?

选项：

A.Investment strategies use a custom index, typically with exclusion criteria

B.Bottom-up financial analysis is performed along with the consideration of ESG factors

C.Portfolios comprise a much larger number of securities compared to portfolios using quantitative strategies

解释：

A. Incorrect because this describes index-based investment within the quantitative management approach. Traditionally, passive or index-based strategies have been the most popular investment vehicles. These impose a custom index, typically with exclusion criteria.

B. Correct because discretionary ESG investment strategies most commonly take the form of a fundamental portfolio approach. A portfolio manager would work to complement bottom-up financial analysis alongside the consideration of ESG factors to reinforce the investment thesis of a particular holding. The portfolio manager would then work to understand the aggregate risk at the portfolio level across all factors to understand correlation and event risks, and potential shocks to the portfolio.

C. Incorrect because this describes the quantitative approach. Quantitative investment strategies are, broadly speaking, rules-based approaches employing the statistical application of financial and/or non-financial factors to drive securities selection. … Where discretionary strategies often focus on depth within a portfolio, manifested through a portfolio of few, more concentrated holdings, quantitative strategies focus on breadth, using a much larger portfolio of holdings to target risk and volatility-adjusted returns.