Which of the following contracts may be changed or voided at one party's discretion?

A voidable contract is a type of contract that one party can choose to affirm or void. This means that if certain conditions or circumstances warrant it, the party with the option can elect to not be bound by the contract, making it possible to void the agreement without facing legal consequences. Common examples of voidable contracts involve contracts with minors or contracts that are based on misrepresentation or undue influence.

In contrast, an implied contract is formed by the actions or conduct of the parties rather than explicit words, and while it can be difficult to change, it isn’t typically voidable at one party's discretion in the same manner. An executed contract is one that has been fully performed by all parties, meaning there are no ongoing obligations that one could terminate at their discretion. An express contract is verbally or writtenly stated and creates obligations that typically cannot be changed unilaterally once the terms are agreed upon. Thus, voidable contracts specifically provide the unique ability to alter or void the agreement at the choice of one party.