Answer: Reciprocity norm
Explanation:
Reciprocity norm is the principle that describes about repaying someone in the same manner in which they have favored us.This repayment is caused due to feeling of obligation. People expect benefit from doing favor for other person as response.
According to the question,reciprocity norm is displayed through scenario of Mrs. Montevecchi feeling obligated for returning favor to religious organization in form of donation because she got Christmas ornament from them as gift.
