Choice "A" is correct. Performing cutoff procedures provides assurance that goods in transit (shipped or received) are appropriately included or excluded from inventory and this procedure is most appropriate for testing the completeness assertion.
Choice "c" is incorrect. Scanning perpetual inventory, production, and purchasing records would only include transactions that have been recorded. The completeness assertion is focused on unrecorded transactions.
Choice "d" is incorrect. Examining paid vendor invoices would exclude invoices from vendors for goods received but not yet billed by the vendor.
Choice "b" is incorrect. Tracing items from the tag listing back to the physical inventory quantities is a test for the existence of the inventory on the tag listing. For the completeness assertion, the auditor should trace from the physical inventory quantities to the tag listing.