Which type of contract depends on chance for its outcome?

The correct choice is an aleatory contract, which is defined by its dependence on an uncertain event or chance for its outcome. In the context of insurance, an aleatory contract involves obligations that are unequal, meaning that one party may pay a relatively small premium while the other party may pay out a much larger benefit depending on the occurrence of a specified event (like an accident, loss, or damage). The reliance on chance, where the insured's premium payments do not equate to the payout value of the policy until a triggering event occurs, exemplifies the essence of an aleatory contract.

For instance, in a typical insurance policy, the insured pays premiums hoping for protection against a loss. If the loss does not occur, the insurer keeps the premium without having to pay anything out, while if the loss does happen, the insurer may pay out a significant sum, showcasing the unpredictable nature of the contract’s performance. This characteristic is what aligns it as an aleatory contract uniquely distinguishing it from other types such as conditions contracts, binding contracts, and unilateral contracts, which do not inherently involve such reliance on chance.