这个题是不是搞错了，正确答案应该是C吧，答案解析看上去也是C，怎么选B呢

NO.PZ2023040601000105问题如下 analyst is given the following information about a portfolio anits benchmark. In particular, the analyst is concerneththe portfolio is a closet inx fun The T-bill return chosen to represent the risk-free rate is 0.50%.Whiof the following three statements es not justify your belief ththe portfolio is a closet inx?I. The Sharpe ratio of the portfolio is close to the Sharpe ratio of the benchmark.II. The information ratio of the portfolio is relatively small.III. The active risk of the portfolio is very low. A.Statement IB.Statement IIC.Statement III A closet inx will have a very low active risk anwill also have a Sharpe ratio very close to the benchmark. Therefore, Statements I anIII are consistent with a closet inx portfolio. A closet inx’s information ratio cinterminate (because the active risk is so low), anoften negative e to management fees. 帮忙一下为何IR是不确定的？谢谢。

NO.PZ2023040601000105问题如下 analyst is given the following information about a portfolio anits benchmark. In particular, the analyst is concerneththe portfolio is a closet inx fun The T-bill return chosen to represent the risk-free rate is 0.50%.Whiof the following three statements es not justify your belief ththe portfolio is a closet inx?I. The Sharpe ratio of the portfolio is close to the Sharpe ratio of the benchmark.II. The information ratio of the portfolio is relatively small.III. The active risk of the portfolio is very low. A.Statement IB.Statement IIC.Statement III A closet inx will have a very low active risk anwill also have a Sharpe ratio very close to the benchmark. Therefore, Statements I anIII are consistent with a closet inx portfolio. A closet inx’s information ratio cinterminate (because the active risk is so low), anoften negative e to management fees. 不公开的指数是个什么东西？这个知识点不记得学过，都有什么结论？用中文列一下，别贴讲义！看不懂