Mario gave his friend eric money for lunch last week. eric feels that he owes mario a favor. this is an example of of social expectations.
a. reciprocity norm
b. social-responsibility norm
c. social exchange theory
d. economic altruism

A. reciprocity norm

Explanation:

Reciprocity norm: The term reciprocity norms related to social expectations is defined as the phenomenon of repaying to the things that others have done for us with kindness. It involves the expectations related to another person in response to respond to one's favor with favor and benefiting each other.

In other words, reciprocity norms in social psychology are defined as a social norm in which an individual responds to a positive action with that of other positive action and because of reciprocity, an individual can build continuing exchanges and relationships.

the vibration from the sound waves messed with the glass and it shattered.

hope this .

answer; sociological imagination;