没有看明白b、c答案的意思

问题如下：

A challenge for asset managers integrating ESG issues is most likely:

选项：

A.a lack of suitable benchmarks.

B.no clear interest from asset owners.

C.a lack of options outside of equities.

解释：

A. Incorrect because the trend toward passive investment and, particularly, investors’ preferences for ETFs, together with the increased availability of ESG data and research, have spurred the market’s development of ESG indexes. As of 2021, there were over 1,000 ESG indexes.

B. Correct because some of the challenges faced by asset managers in integrating ESG issues include a lack of clear signals from asset owners that they are interested in ESG investing.

C. Incorrect because ESG offerings by asset managers generally began with active-listed equities but recently evolved to other asset classes.