Cialdini and colleagues asked people if they would be willing to chaperone juvenile delinquents on a field trip to the zoo. This research showed that people would be most willing to do so if ________.
1) they themselves had been juvenile delinquents in their youth.
2) they had first refused to make a long-term commitment to working with juvenile delinquents.
3) they had received monetary incentives for serving as chaperones on the field trip.
4) they had first witnessed other people agreeing to serve as chaperones.