When a broker or their agent, acting on behalf of a client, has a competing professional or personal bias which hinders their ability to unreservedly fulfill the fiduciary duty they have undertaken, this is referred to as a (n)
conflict of interest.
A personal bias suggests a conflict of interest. The other choices would be inappropriate to the question. Agency, whether dual agency or subagency, would imply a relationship with the client as opposed to some personal or professional conflict.