Final answer:
Reciprocation is the reason why a person says "yes" to repay a favor.
Step-by-step explanation:
When a person says "yes" because he/she owes the person a favor, that person is saying "yes" because of reciprocation. Reciprocation is a social norm that encourages people to repay favors or benefits they have received. It is a form of exchange where one person reciprocates a favor or service to maintain a sense of fairness and social cohesion.