The $4 call options will expire worthless if it closes below $4 tomorrow. So the person that bought the call will get nothing, and will have lost all the money they spent buying the call. The person selling the call keeps all the money they received for selling the call option, and gets to keep all their shares that were used to cover that call. 

The seller of the call wins. 

We don't really have to deal with this every week Bud, since the weekly options aren't traded much. It's the monthly options, that expire the 3rd Friday of each month, that are more heavily played, and have more influence.