Dana is working with a client to decrease the number of cigarettes they smoke per day. Dana collects baseline and determines the client is smoking an average of 10 cigarettes per day. Dana implements a DRL procedure in which the client will earn five dollars if they have smoked no more than eight cigarettes per day for an entire week. next, the client will earn five dollars if they have smoked no more than six cigarettes per day. Then, no more than four cigarettes per day, and so on, until the client has quit smoking for at least one month. Which experimental design is Donna using