Answer:
Social norm of norm of reciprocity
Step-by-step explanation:
This form is a social expectations that people will respond to each other in kind returning benefits for benefits, and responding with either indifference or hostility to harms. The social norm of reciprocity often takes different forms in different area of social life, or in different societies. All of them, however, are distinct from related ideas such as gratitude, the Golden rule or mutual goodwill.