Final answer:
Reciprocity is exemplified when Walter sharing about his divorce leads to Susan sharing a similar experience. It highlights the mutual exchange of personal information in relationships.
Step-by-step explanation:
In the context of self-disclosure principles, the principle exemplified when Walter shares about his parents' recent divorce, prompting Susan to reciprocate by revealing that her parents divorced when she was very young, is A) Reciprocity. This principle refers to the mutual exchange of personal information in a relationship, creating a two-way street of openness and trust. When one individual discloses personal information, it often leads to a similar disclosure from the other party, promoting closer and more intimate connections.