Broker Able listed a home for sale under an exclusive-right-to-sell listing. Broker Baker cooperated with Able in a co-brokerage. The house was sold and the commission split between Able and Baker. Which of the following is (are) true? I) The selling broker, Baker, is a sub-agent of the listing broker; II) The listing broker, Able, is an agent of the seller; III) Both brokers are sub-agents of the seller; IV) A broker who is not the seller's agent cannot receive any part of the commission