A sales agent had a listing and the property did not sell. The listing expired. During the term of the listing the seller had disclosed confidential information to the agent. Several months later, the agent has a buyer client interested in purchasing the same property. How long must the seller's private information be kept confidential?
a) Indefinitely
b) Until the property is sold
c) Until the agent's relationship with the seller ends
d) Until the information becomes public knowledge