Final answer:
Without a buyer's representation agreement, the broker owes a duty of fairness to the buyer instead of confidentiality or loyalty, which require a fiduciary relationship established through a formal agreement.
Step-by-step explanation:
If a broker brings a buyer to a seller but did not sign a buyer's representation agreement with the buyer, the duty that is still owed to the buyer is fairness. While confidentiality and loyalty are typically duties owed to a client under a fiduciary relationship, fairness is a basic ethical duty owed to all parties in a transaction, regardless of whom the agent represents. Without a signed agreement, the buyer is not formally represented by the broker; hence, the duties of loyalty and confidentiality are not obligatory.