Final answer:
An auditor would sample from the source documents to the general ledger to best test existence.
Step-by-step explanation:
An auditor would sample from the source documents to the general ledger to best test existence. This is because the source documents contain original records of transactions, such as invoices and receipts, while the general ledger is the central repository that summarizes all the transactions. By sampling from the source documents to the general ledger, auditors can verify that the recorded transactions actually occurred.