Final answer:
According to the NAR Code of Ethics, the acceptable reason for not cooperating with a broker is related to the broker's agency fees, as personal conflicts, track record, and ethnicity are not valid or ethical reasons.
Step-by-step explanation:
The subject of this question is real estate and the ethical guidelines that those within the industry must follow, according to the National Association of Realtors (NAR) Code of Ethics. When considering the list of reasons for not cooperating with a broker, the acceptable reason according to the NAR Code of Ethics would be the broker's agency fees. Other reasons such as personal conflict, poor track record, and the broker's ethnicity are not ethical grounds for refusal to cooperate.
The broker's personal conflicts or poor track record with you are professional disagreements and do not justify unethical behavior. Meanwhile, discrimination against a broker based on ethnicity is strictly prohibited under the NAR Code of Ethics and also violates fair housing laws. Deciding not to cooperate with a broker because of their agency fees is related to the business aspect and is considered a legitimate business decision.