请问，这道题怎么做呢，没有很理解

问题如下：

A risk manager at a hedge fund currently uses historical data to estimate the future volatility of a portfolio of US equities. To improve on the current methodology, the manager is considering adding the use of implied volatility of the equity assets, while also assessing the potential drawbacks of using this metric. Which of the following correctly describes a weakness of implied volatility as a predictor of future volatility?

选项：

A.

Broad indexes of implied volatility do not exist, making forecasting the volatility of broad asset classes difficult.

B.

Implied volatility is a backward-looking measure, which limits its usefulness in estimating future volatility.

C.

Implied volatilities are not available for assets that do not have actively traded options.

D.

In practice, implied volatilities differ for options with different maturities on the same underlying asset, even though theory suggests they should be the same.

解释：

Explanation

C is correct. Options are not actively traded on all assets; in these instances, reliable implied volatilities are not available.

A is incorrect. Volatility indexes exist that track the implied volatility of several major asset class indexes, including the S&P 500 (i.e. the “VIX”), commodities, interest rates, currencies, and other stock indexes.

B is incorrect. Implied volatilities are forward looking, whereas the volatilities calculated from historical data are backward looking.

D is incorrect. Implied volatilities for options of different maturities on the same underlying do indeed differ. However, these implied volatilities for different maturities give an indication of average volatility expected over the respective time periods. Because volatility exhibits mean reversion, we do not expect implied volatilities to be the same for options of all maturities.

Section Valuation and Risk Models

Learning Objective Evaluate implied volatility as a predictor of future volatility and its shortcomings.

Reference Global Association of Risk Professionals. Valuation and Risk Models. New York, NY: Pearson, 2022. Chapter 3. Measuring and Monitoring Volatility.