Idris started going to her local BuyItAll when she received a letter congratulating her on her high school graduation and offering her a one-time 20% off her entire purchase coupon. When she settled into her first apartment, she used the coupon and signed up for their rewards program. Idris receives intermittent coupons from BuyItAll for $5, $10, and sometimes 20% off a single purchase. She is a loyal shopper, often purchasing more than the items that qualify for her coupons. BuyItAll is using

a continuous reinforcement schedule.

an approximation sequence.

a shaping procedure.

reinforcement

a partial reinforcement schedule.