In a unilateral contract involving a performance, when is the offer considered accepted?

In a unilateral contract, acceptance occurs through the performance of an act rather than through a promise to perform. This type of contract is commonly seen in scenarios such as rewards for a lost item—where the completion of the act (finding the lost item) constitutes acceptance of the offer.

The correct choice relates to the principle that acceptance of a unilateral contract is generally recognized when a substantial amount of the task has been completed. This means that the party making the offer can no longer withdraw the offer once the offeree has begun performance in a significant way.

This acknowledges that the offeree has demonstrated their commitment to fulfilling the conditions of the contract, and it is the action taken towards completing the task that indicates acceptance. Thus, the essence of the choice highlights that there must be a meaningful level of commitment to the task, which is viewed as acceptance of the offer in legal terms.