Final answer:
A unilateral contract is where only one party makes a promise to perform an action, contingent upon the other party's performance of an act.
Step-by-step explanation:
The contract that would best be described as one in which only one party makes a promise to perform an action is a unilateral contract. A unilateral contract is where only one party makes a promise to perform an action, contingent upon the other party's performance of an act.
In a unilateral contract, one party, known as the offeror, makes a promise in exchange for the performance of an act by the other party, known as the offeree. If the offeree decides to carry out the act, the offeror is obligated to fulfill the promise.
This contrasts with a bilateral contract, where both parties make promises to each other. Implied contracts and implied-in-fact contracts are terms used to describe agreements inferred from the conduct of the parties or the circumstances of the case rather than explicit promises.