A buyer mailed an offer to purchase a property at the full price and terms of a listing agreement. Which of the following essential elements is missing to form a valid contract?

Consideration refers to something of value exchanged between the parties, which is necessary for a contract to be enforceable. In this scenario, the buyer submitted an offer that implies consideration, as the buyer is proposing to pay the full price for the property. Therefore, consideration is present and not the missing element.

Earnest money is a deposit made to demonstrate the buyer's commitment to the purchase, but it is not an essential element required to form a valid contract. While it can strengthen the buyer's position and indicate serious intent, a contract can still be valid without an earnest money deposit, provided that acceptance occurs.

Legal purpose ensures that the contract’s objectives are lawful and not against public policy. In this case, the transaction of purchasing a property is legal, so the element of legal purpose is present. Thus, it does not represent a missing element in the formation of a valid contract.