The effective date of a Florida real estate contract is:

Option A is incorrect because the buyer's signature alone doesn't create a binding contract. It merely initiates the process by making an offer, which requires acceptance by the seller to become enforceable.

Option B is incorrect because the seller's signature alone doesn't automatically create a binding contract. The seller must accept the specific terms as offered by the buyer, not just unilaterally sign a document.

Option D is incorrect because earnest money is a separate consideration and doesn't create contractual obligations. While its deposit may be required by the contract, it doesn't establish the effective date of the agreement itself.