问题如下：
Compared to at-the-money currency options, out-of-the-money currency options exhibit which of the following volatility traits?
选项：
A.Lower implied volatility
B.A frown.
C.A smirk.
D.Higher implied volatility
解释：
D is correct. Away-from-the-money currency options have greater implied volatility than at-the-money options. This pattern results in a volatility smile.
at the money currency 的implied sigma不是应该是最小的吗
