(C) The requirement is to give the financial statement assertion that is most likely to be the focus of an auditor in his procedures when considering accounts payable. The simple net profit equation is revenue minus expense equals profit. Expenses are created when accounts payable are booked. If management wants to keep profit high they can either report higher sales or lower expense. Choice (C), completeness, is the one assertion that applies most to accounts payable because if accounts payable owed are omitted, net income is too high (i.e. overstated). Choice (A) is false because the existence assertion deals with whether recorded accounts payable are overstated, understating net income, something management is unlikely to let happen. Choice (B) is mistaken because payables have few onerous disclosures. Choice (D) is not the case because there is usually no valuation questions regarding payables - they are valued at the cost of the related acquisition unless there is a chance of non-payment or reduced payments. See ISA 500 for more information on management's financial statement assertions.