2 For example, A buys a put option with USD/JPY of 1: 90 and the expiration date of the option is three months later. Three months later, the dollar against the yen was 1:70. At this time, Party A chooses to exercise the option and can earn 200 basis points according to the foreign exchange rate. If Party A bought 1000 lots at that time, his family could earn 1000*200 yen three months later, that is, the net profit after three months was 1000*. If USD/JPY is 1: 1 10 after three months, and if A exercises the option, the income will be negative (1000*200+A), then A will give up exercising the option, that is, lose a limited option fee.