Mary Smith is broker-in-charge of Smith Realty, which has several affiliated agents. Mary is actively involved in listing and selling properties. Sue Long, a provisional broker with Smith Realty, has a buyer client who has expressed interest in one of Mary's listings. Which of the following agency agreements is permissible in this situation?

- Mary and Sue may act as dual agents.
- Mary and Sue may act as designated agents.
- Mary and Sue may both represent the seller, treating the buyer as a customer.
- Mary may represent her seller, and Sue may represent her buyer.