Which arrangement is an example of a unilateral contract?

• A. Open listing
• B. Lease option
• C. Exclusive right to sell
• D. Open listing & option

Answer: (D)

A unilateral contract is formed when one party makes a promise that can only be accepted by the other party’s performance. In real estate, a classic example is an option to purchase: the seller promises to sell at a set price, but that promise becomes enforceable only if the option holder exercises the option by performing (for example, paying the option fee or giving notice). The key is that the buyer’s act of exercising is what accepts the promise; the seller’s promise to sell is not binding until that act occurs.

An open listing fits this pattern as well because the seller promises to pay a commission only if a broker successfully procures a buyer. The broker’s obligation to earn the commission depends on performing the act of bringing a buyer; until that happens, there’s no binding payment obligation on the seller. In contrast, an exclusive right to sell creates mutual promises: the broker agrees to market the property and the seller agrees to pay a commission if the property is sold, regardless of who finds the buyer, which makes it bilateral. A lease option blends a lease (bilateral) with an option (unilateral), but the whole arrangement isn’t purely one-sided.

Therefore, combining an open listing with an option showcases unilateral contract elements most clearly.