Final answer:
The correct answer to the question is B. a multiple listing clause. This clause is used to list a property on a multiple listing service, expanding its market exposure.
Step-by-step explanation:
The provision in a contract with a property seller that gives additional authority to the broker and obligates the broker to alert other brokers to the availability of the property is B. a multiple listing clause. This clause allows the property to be listed on a multiple listing service (MLS), which is a database that real estate brokers use to share information about properties with other brokers who may represent potential buyers.
By including a multiple listing clause, property sellers ensure that information about their property reaches a wide audience, increasing the chances of finding a suitable buyer. It is important that individuals or firms own the property to enter into such a contract, as they have the right to decide how their property is marketed and to whom they enter into contracts with.