What must a customer submit to finalize a transaction?

Finalizing a transaction typically involves completing the payment process, which is why submitting payment is essential. Payment represents the customer's agreement to the terms of the transaction and is the action that allows the transfer of goods or services in exchange for money. Without this step, the transaction is not considered complete, as there is no exchange or commitment from the customer.

Other documents like an invoice or a receipt may follow the transaction, serving as proof of the transaction or a record of the sale, while an order form is generally used to initiate the transaction rather than finalize it. Therefore, the payment itself is the crucial element that signifies the conclusion of the transaction.