Your friend Rick has offered to take you out to dinner if you help him move his couch. However, after you help him he asks for additional help with other tasks around his house, like cleaning out the garage, watering the plants, and mowing the lawn. In this situation, Rick has used:

a. the door-in-the-face technique.
b. central route persuasion.
c. the peripheral route technique.
d. the lowball technique.