(a) A real estate broker or principal real estate broker who has entered into:
(A) A listing agreement with a seller;
(B) A service contract with a buyer to represent the buyer; or
(C) A disclosed limited agency agreement; or
(b) An individual licensed under ORS 696.022 (Licensing system for real estate brokers and property managers) who has entered into a written contract with a real estate broker or principal real estate broker to act as the broker's agent in connection with acts requiring a real estate license and to function under the broker's supervision.