追加提问A/B哪个更合适，选B吗？因为delta更大，如果不考虑成本，谢谢

问题如下：

In regard to using USD/EUR options, Peixaria is least likely to recommend a strategy to go:

选项：

A.

long an equal number of 25-delta puts and calls.

B.

long an equal number of 50-delta puts and calls.

C.

short an equal number of 15-delta puts and calls.

解释：

C is correct. A short strangle (short an equal number of 15-delta calls and puts) would only be appropriate if volatility is expected to be low. The expectation is for increased volatility, so the long strangles would be more appropriate. A strategy of taking long positions on an equal number of 50-delta calls and 50-delta puts (i.e., a 50-delta straddle) is an appropriate way to take advantage of expected increased volatility in the USD/EUR currency pair. However, 50-delta calls and puts are at-the-money options and are more expensive than out-of-the-money options, such as 25-delta calls and puts (a 25-delta strangle).

A is incorrect. A long 25-delta strangle is appropriate if you expected increased volatility. This strategy is a cheaper than the 50-delta strangle because 50-delta calls and puts are at-the-money options and are more expensive than out-of-the-money options such as 25-delta calls and puts (a 25-delta strangle).

B is incorrect. A long 50-delta strangle (long 50-delta calls and puts) would be appropriate if you expected high volatility.

中文解析：

由于预测波动率增加，所以应该做多波动率，A选项是构建了一个long strangle策略；B选项是构建了一个long straddle策略，都是做多波动率的策略，因此是可以的。

而C选项是构建了一个short strangle的策略，是做空波动率，不对。