不考虑 profit 的理由是否是因为权利金是沉没成本？

问题如下：

Put option will be exercised at expiration :

选项：

A.

when stock price is above the strike price.

B.

when stock price is below the strike price plus the premium.

C.

when stock price is below the strike price.

解释：

C is correct. Only when stock price is below the strike price, the investor would exercise the put option.

中文解析：

判断期权是否值的行权，比较行权价和现货价。对于看跌期权，当现货价格小于执行价格时，行权，C对。

判断行权是否可以使得profit大于0时，才需要考虑期权费，考虑break even point。