$4.$ You are thinking about robbing a bank but there is a law against this sort of behavior. If you are caught and convicted, you can expect to serve $4$ years in jail. If you take a gun with you and kill the bank teller, who can identify you, it may reduce the chances of getting caught. However, there is a law against murder and if you are caught and convicted, you can expect to serve $12$ years in jail. Assume the courts do not add the sentence for one crime on to another. You decide to rob the bank and you are standing at the teller window putting the money into a bag. What is the marginal cost of killing the teller?Question $4$ options:a$)4$ years in jailb$)6$ years in jailc$)8$ years in jaild$)12$ years in jaile$)16$ years in jail