Answer:
Answer is option A, i.e. An offer of sub-agency to all members of a MLS.
Step-by-step explanation:
A blanket unilateral offer can be understood as an offer of compensation and cooperation to all the listings that are mentioned in MLS. This is generally a result of an agreement between the brokers and seller in which the broker is authorized to compensate and cooperate with all the participants of MLS. MLS, also known as multiple listing services, that can be understood as various technological as well as non-technological services used by real estate brokers which enable them to see through all the listings of various properties for sale.