Which of the Following Promotions Is Intended to Help the Advertiser

Which of the following promotions is intended to help the advertiser meet the goal of habit reinforcement?

A) For every ten cups of coffee you purchase at a local convenience store, you get one free.
B) A salesclerk gives out free samples of Bush's brand home style chili at Sam's Club.
C) Sam sees a comparative ad showing the superiority of Coors beer over Anheuser-Busch beer.
D) A vacuum cleaner salesperson offers to clean the living room carpet of the Truman household.
E) A new laundry shop offers a one-time free trial for all customers.