Which of the following 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 only one party makes a promise and the other party accepting by performing the requested act. An option to purchase fits this: the seller promises to sell at a set price if the option is exercised, but the option holder has no obligation to buy until they choose to exercise. An open listing also aligns with this idea: the owner does not promise to pay a commission upfront; a commission is earned only if a broker actually procures a buyer. In contrast, an exclusive right to sell involves promises from both sides—the broker promises to market the property, and the owner promises to pay a commission regardless of who procur es the buyer—so that arrangement is bilateral. The combination of an open listing and an option thus illustrates unilateral contracts, which is why it’s the best example.