Answer: B) may be liable to the seller for violating duties required by the listing agreement.
Explanation:
The Multiple Listing Service (MLS) is a database that allows brokers to cooperate in finding buyers for homes. They list the properties for sale and if other brokers know people who need such a house they will reach out and buy it. The listing broker and the selling broker will then share commissions.
This is what the broker was trying to avoid by withholding the information from the MLS.
However, the broker is in violation of the listing agreement which stated that he should post it on the MLS within 3 working days and as such there is a very real chance that he is liable to the seller for this violation.