Delightful Weddings, LLC, and Event Catering Inc. have an executory contract. They agree to rescind their contract and simultaneously enter into a new contract. If the initial contract was subject to a preexisting duty, the new contract will most likely be

D. Unenforceable

Explanation:

Preexisting duty is a contractual law whereby there is no consideration given for any changes of the contract and the changes is therefore voidable. Thus, when there's a preexisting duty, it does not constitute valid consideration for a new promise. As such, because consideration cannot consist of performance that the party had a pre-existing duty to perform, it makes new contracts unenforceable.