Single agent shall mean a limited agent who has entered into a brokerage relationship with and therefor represents only one party in a real estate transaction. A single agent may be one of the following:

(1) Buyer's agent, which shall mean a licensee who represents the buyer in a real estate transaction;

(2) Landlord's agent, which shall mean a licensee who represents the landlord in a leasing transaction;

(3) Seller's agent, which shall mean a licensee who represents the seller in a real estate transaction; and

(4) Tenant's agent, which shall mean a licensee who represents the tenant in a leasing transaction.