Miss Simpson's fifth grade class will not stop leaving their seats! The movement is so disruptive to the lessons that at times she cannot concentrate on what she is teaching because she is asking students to sit down. She develops a plan that focuses on keeping the students in their seats. She tells the class that for every 15 minutes every student stays in their seat, the class will receive a check mark on the board in the front of the room. If they collectively earn 5 check marks in a day, they will each be given a ticket which they can collect and trade for items in a treasure box. Which type of group contingency has Miss Simpson put in place?

a. independent

b. interdependent

c. dependent

d. hero procedure