After Mrs Chanski and Her Children Had Helped Themselves to Free

Multiple Choice

After Mrs. Chanski and her children had helped themselves to free samples of the cookies being promoted in the grocery store, she felt obligated to buy some, even though they seemed unreasonably expensive. Her reaction best illustrates the significance of

A) social facilitation.
B) the reciprocity norm.
C) the bystander effect.
D) the just-world phenomenon.