Just so you know, while a sales contract calls for earnest money, not paying the required earnest money per contract only puts the buyer in breach of contract and does not nullify the contract
"If you agree to pay earnest money but do not make the required payment or your earnest money check â€œbounces,â€ you will probably be considered in breach of the contract."
Our Texas contracts say: "If Buyer fails to deposit the earnest money as required by this contract, Buyer will be in default."
The consideration that William wrote about refers to the purchase price stated in the contract, which is an integral part of what constitutes a valid contract.
I'm not sure what state you are in, but Sandy is right when it comes to Texas contracts regarding the option period.