问题如下：
At expiration, a European put option will be valuable if the exercise price is:
选项：
A. less than the underlying price.
B. equal to the underlying price.
C. greater than the underlying price.
解释：
C is correct.
A European put option will be valuable at expiration if the exercise price is greater than the underlying price. The holder can put (deliver) the underlying and receive the exercise price which is higher than the spot price. A European put option would be worthless if the exercise price was equal to or less than the underlying price.
老师你好！ 这个题转不过来弯，put option, 应该是在价格下跌时候才会行权，所以应该是交易价格低于标的物价格，才有意义，否则不行权。这么理解对吗？