In contract law, what is typically required for a valid agreement?

A valid agreement in contract law fundamentally requires mutual consent among all parties involved. This concept, often referred to as "meeting of the minds," is essential because it signifies that all parties have a shared understanding and agreement on the terms of the contract. Without this mutual consent, there can be no enforceable agreement.

In practice, this means that each party must accept the offer made by the other party, and such acceptance must be communicated effectively. This mutual agreement implies that the parties are voluntarily entering into the contract without coercion or undue influence, ensuring that they recognize and agree upon their respective rights and obligations.

The other choices do not fulfill the fundamental requirement for a valid agreement. For instance, a unilateral decision from one party lacks the necessary agreement from all parties, therefore negating the existence of a contract. Similarly, while written documentation can provide evidence of a contract's existence, it is not always required for a contract to be valid, as many contracts can be legally binding even if they are verbal. Lastly, a public announcement does not create an obligation or a binding contract and does not satisfy the requirement of mutual consent.