Final answer:
When benefits are proportional to contributions in a relationship, equity exists. This concept aligns with the principles of social exchange theory, where individuals feel satisfied when there is a fair balance between what they give and receive in a relationship.
Step-by-step explanation:
When benefits are proportional to contributions in a relationship, C. equity exists. In social exchange theory, equity is central to a person's assessment of their relationships; people want to maximize the benefits and minimize the costs, and they feel most satisfied when there is a balance or fairness in their social exchanges. This means the perceived benefits one receives are proportionate to what one contributes. Companionate love does refer to a type of love that includes intimacy and commitment, often found in close friendships and family, but it does not inherently involve a proportional balance between benefits and contributions.