Final answer:
When a broker has a relationship of trust and confidence with a client, it is called a fiduciary relationship, where the broker must act in the best interest of the client.
Step-by-step explanation:
When a broker has a relationship of trust and confidence with a client, this is known as a fiduciary relationship. The term fiduciary refers to a situation where one party, in this case, the broker, has a legal and ethical obligation to act in the best interest of the other party, which is the client. This is different from subordination, hypothecation, or non-agency relationships that have different legal implications and do not necessarily involve a trust relationship.