Which element is necessary for a unilateral contract to be established?

A unilateral contract is characterized by a single promise made by one party in exchange for a specific performance by another party. This means that one party makes a promise that can only be accepted by the other party performing a certain action. For instance, if someone offers a reward for the return of a lost item, the reward is only payable when the item is returned; there’s no reciprocal promise involved. This clear demonstration of a one-sided promise leading to performance is what solidifies the nature of a unilateral contract.

In contrast to other options, a two-way promise or multiple parties would indicate a bilateral contract scenario, while written confirmation is not a requirement for the validity of a unilateral contract. Instead, the focus is on the performance being the acceptance of the promise. Thus, the essential element for a unilateral contract is indeed a single promise exchanged for performance.