这个题要怎么理解

问题如下：

All else being equal, which of the following options would cost more than plain-vanilla options that are currently at-the-money?

I.  Lookback options

II.   Barrier options

III.  Asian options

IV.  Chooser option

选项：

A.

I only

B.

I and IV

C.

II and III

D.

I, III, and IV

解释：

ANSWER: B

Lookback options use the maximum stock price over the period, which must be more than the value at the end. Hence they must be more valuable than regular European options. Chooser options involve an additional choice during the life of the option, and as a result are more valuable than regular options. Asian options involve the average, which is less volatile than the final price, so must be less expensive than regular options. Finally, barrier options can be structured so that the sum of two barrier options is equal to a regular option. Because each premium is positive, a barrier option must be less valuable than regular options.