You don't have to undertake the obligation of sales. Binary tree pricing model is the pricing of American options, which means that the option buyer has the right to sell goods or futures to the option seller at a certain price within a specified time, but the difference is that it does not undertake the obligation to sell. Put option is also called put option, put option and put option. In the transaction of put options, investors who buy put options are optimistic that the price will fall, so they buy put options, while investors who sell put options expect the price to rise or not.