Which of the following is NOT one of the essential elements for a valid contract?

A valid contract typically requires several foundational elements to be enforceable. Consideration is essential, as it refers to the value exchanged between parties, thereby providing a reason for each party to enter into the agreement. Mutuality is also necessary; this means that both parties must understand and agree to the terms of the contract, signifying that they are on the same page and committed to the agreement.

While written documentation can certainly add clarity and serve as evidence of the terms agreed upon, it is not strictly required for a contract to be valid in many jurisdictions. Oral contracts can also be legally binding as long as they contain the essential elements like consideration and mutuality.

Implied consent refers to consent that is inferred from a party's actions rather than explicitly stated. While it can play a role in some agreements, particularly in ongoing relationships (like employment), it is not one of the fundamental requirements for a contract to be considered valid. Therefore, implied consent is not essential in the same way that consideration and mutuality are, making it the correct answer to the question presented.