Which of the following is required for a contract to be binding?

For a contract to be binding, mutual consent is a fundamental requirement. This means that all parties involved must agree to the terms of the contract, demonstrating a clear understanding and acceptance of what is being offered and agreed upon. Mutual consent indicates that there has been an offer made by one party and an acceptance of that offer by another, which is crucial for the formation of any legal agreement.

While having a written agreement can provide clarity and serve as evidence of the contract, it is not strictly necessary for all contracts. Many oral contracts can also be binding, provided they meet certain criteria. Witness signatures may add an additional layer of validity or credibility, but they are not universally required for the creation of all contracts.

Thus, the correct choice reflects that mutual consent is essential for a contract to be considered binding, aligning with fundamental principles of contract law.