Final answer:
The agent-client relationship is a fiduciary one, where the agent must act in the client's best interests and prioritize their needs. Hence, option (C) is correct.
Step-by-step explanation:
The relationship between an agent and a client is best described as C. fiduciary. This type of relationship involves a trust and ethical bond where the agent has a legal duty to act in the client's best interests. It implies a higher standard of behavior than just a commercial or business relationship because the agent must prioritize the client's needs and interests above their own.
Unilateral refers to a one-sided or one-party relationship that does not capture the mutual obligations inherent in a fiduciary relationship. Exclusive typically refers to an exclusive agency or exclusive representation, which, while related, doesn't specifically address the fiduciary duties and obligations. The last option is not directly related to the nature of the agent-client relationship.