To make this change Boxes R Us has a manager pay out to each box maker a dollar every time they finish box. Sure enough this increases productivity but every time the manager takes a break productivity drops to nothing. How would you recommend they change procedure to best limit this loss of productivity?

a$)$ Use a primary reinforcement rather than money

b$)$ Increase the time between when the box is made and when they are paid

c$)$

Randomly change the number of boxes they have to make to get paid

Pay for every $3$ boxes instead of every single box