Which test of controls can help ensure that goods shipped are properly billed?

The correct choice emphasizes the importance of matching shipping documents with sales invoices as a test of controls to ensure that goods shipped are accurately billed. This procedure is critical in the accounts receivable process. By examining the shipping documents, such as bills of lading or packing slips, and ensuring that they are appropriately matched to corresponding sales invoices, auditors can verify that the goods dispatched to customers are indeed billed correctly for the correct quantities and prices.

If there is a proper match between the shipping documents and the sales invoices, it provides a strong indication that the transaction has been recorded accurately, thus reducing the risk of billing discrepancies and potential revenue loss. This control can detect and prevent errors or fraud, ensuring that revenue is recognized only when goods have been shipped and documented.

While other options could relate to aspects of monitoring or validating sales processes, they do not directly ensure the accurate billing of goods shipped in the same comprehensive manner as matching shipping documents to sales invoices.