Choice "A" is correct. Because of the significant discrepancies on past confirmations, the auditor would most likely choose to use individual invoices in the current year's audit. Depending on the client's accounting system, these invoices could provide more confirmation detail including individual transactions instead of a balance at a point in time. By confirming individual transaction detail on the individual invoices, there should be fewer discrepancies than confirmations sent out to customers in years past. Choice "b" is incorrect. An auditor is unlikely to focus the confirmation process on customers with credit balances because credit balance accounts receivable are unlikely to be overstated. Confirmation is primarily a test of existence, or overstatement. Choice "c" is incorrect. When confirming accounts receivable, the auditor is unlikely to focus on confirming small account balances because misstatements in accounts with small balances are unlikely to be material and because the confirmation process is primarily a test of existence, or overstatement.Choice "d" is incorrect. The confirmation process typically does not focus on overdue balances because confirmation is primarily a test of existence and not valuation.