In Colorado, a licensee may act as a transaction broker only when both parties consent in writing to that relationship and to the duties owed to all parties. This written consent confirms that the broker will facilitate the transaction while remaining neutral and not representing either party as a fiduciary, but still providing useful services and information to both sides. Verbal consent isn’t enough, and consent from only one party isn’t sufficient because the transaction-broker role involves duties to all parties, not loyalty to a single client. Consent after closing isn’t valid for defining the relationship in the transaction. So, the best choice reflects the requirement that both buyer and seller agree in writing to a transaction-broker relationship with duties owed to everyone involved. If only one party’s consent were given, or the consent weren’t in writing, the licensee would need to act in a different capacity, such as a single agent for one party or a non-representative intermediary.