Doing a favor for someone because they have helped you in the past illustrates

A) conflict.
B) cost-benefit analysis.
C) the reciprocity norm.
D) the social-responsibility norm.

Reciprocity Norm

The reciprocity norm is a social norm that expects individuals to respond to each other in kind, returning benefits for benefits received.

Favor

An act of kindness beyond what is usual or expected, often involving giving someone an advantage or showing support.

Past

The period of time or a segment of history that has already occurred, distinguished from the present and future.