Final answer:
The listing agreement is a contract between the seller and the broker.
Step-by-step explanation:
The listing agreement is a contract that outlines the terms and conditions between the seller (B) and the broker (A) when it comes to selling the home.
Although in this scenario there is no written agreement, there is still an implied contract between Seller B and Broker A due to their agreement and understanding that Broker A will be paid if he can sell the house.