What type of contract is defined by one party fully performing while the other has not?

The correct choice is characterized as a partially executed contract. This type of contract occurs when one party has completed their obligations, but the other party has not yet performed their responsibilities as per the agreement. The essence of a partially executed contract lies in the imbalance of performance: one side has fully fulfilled its part, while the other has fallen short. This situation creates a pending obligation for the party that has yet to perform, and the contract remains active until all parties have completed their respective duties.

In contrast, an executed contract refers to an agreement where both parties have completed their respective performances. An executory contract is one in which obligations remain to be fulfilled by one or both parties, not necessarily indicating that any part of it has been completed. A bilateral contract is simply an agreement involving mutual promises made by two parties, and it doesn't encapsulate the performance status of the obligations. Understanding these distinctions helps clarify how obligations interplay in various contractual situations.