A contract in which only one party to the contract is legally bound to do anything is

Aleatory contracts involve an element of chance or uncertain events, where the performance of one party depends on the occurrence of a specific event. While an aleatory nature can exist in unilateral contracts, it does not define the one-sided obligation aspect. Therefore, this choice does not accurately describe the binding nature of unilateral contracts.

Conditional contracts are agreements that depend on the occurrence of a specific condition or event before obligations are enforced. Although unilateral contracts can be conditional, the defining feature of a unilateral contract is its one-sided obligation rather than the presence of conditions. Thus, this choice fails to capture the essence of a unilateral contract.

Personal contracts pertain to agreements that are specific to individuals based on their unique characteristics or qualifications. This term does not relate to the binding nature of the contract; rather, it describes the type of parties involved. Therefore, personal contracts do not adequately convey the concept of one party being legally bound.