The buyer has just signed a buyer's agency agreement with a broker. The buyer has agreed to pay the broker a specific fee. Under the common law of agency, the relationship between the buyer and the broker would best be described as

The term "agreement agency" is not a standard legal term recognized in agency law. While it suggests a relationship based on an agreement, it fails to capture the specific nature of express agency where explicit terms are communicated and agreed upon. Therefore, this choice does not accurately reflect the established legal framework governing agency relationships.

Implied agency arises from the conduct of the parties rather than a formal agreement. It occurs when a broker acts on behalf of a buyer without an explicit agreement being established. In this scenario, since the buyer has signed a formal agreement to pay the broker, the relationship cannot be classified as implied, making this choice incorrect.

Gratuitous agency refers to a situation where an agent acts without expecting any compensation from the principal. In this scenario, since the buyer has agreed to pay a fee to the broker, the relationship cannot be classified as gratuitous, which would imply no payment or formal compensation for services rendered.