What type of contract requires only one party to make an enforceable promise?

A unilateral contract is defined by the commitment made by only one party, which is binding and enforceable upon acceptance by the other party. In this type of contract, one party makes a promise in exchange for a specific action or performance from the other party. The classic example is a reward contract, where one party promises to pay a reward if someone fulfills a condition, like finding a lost pet.

The other choices present different forms of contracts with distinct features. A bilateral contract involves mutual exchanges of promises, where both parties have obligations to fulfill. An implied contract is formed through the actions or conduct of the parties rather than written or spoken words, and a conventional contract is generally understood as a formal agreement between parties. Thus, the unique nature of a unilateral contract, emphasizing a one-sided promise that leads to an obligation upon fulfillment by the other party, solidifies its role in contract law.